/* ============================================
   Course Engine - Shared Styles
   ============================================ */

/* ============================================
   1. CSS Variables — Design Token Foundation
   ============================================ */
:root {
    /* Surface layers — cool violet-black */
    --bg-base:       #13111B;
    --bg-surface:    #1B1926;
    --bg-elevated:   #232030;
    --bg-overlay:    #2C2840;
    --bg-muted:      #38344E;

    /* Borders — cool */
    --border-subtle:  #2C2840;
    --border-default: #3C3858;
    --border-strong:  #504B68;

    /* Text — lavender-tinted cream */
    --text-primary:   #E2DEF0;
    --text-secondary: #9890AC;
    --text-tertiary:  #6B6380;
    --text-ghost:     #4A4260;

    /* Accent palette — purple-centric */
    --amethyst:       #A78BFA;
    --amethyst-dim:   #8B73DE;
    --amethyst-glow:  rgba(167, 139, 250, 0.12);
    --amethyst-subtle: rgba(167, 139, 250, 0.06);
    --amber:          #E0976A;
    --amber-dim:      #C87E52;
    --amber-glow:     rgba(224, 151, 106, 0.12);
    --slate:          #7CB4E0;
    --slate-glow:     rgba(124, 180, 224, 0.12);
    --sage:           #8CC68C;
    --sage-glow:      rgba(140, 198, 140, 0.12);
    --gold:           #D4B87A;
    --coral:          #E06070;
    --coral-glow:     rgba(224, 96, 112, 0.12);
    --lavender:       #C4A8E8;
    --lavender-glow:  rgba(196, 168, 232, 0.12);

    /* Syntax highlighting */
    --syntax-keyword:  #C4A8E8;
    --syntax-string:   #A6D4A6;
    --syntax-function: #8CC4E8;
    --syntax-type:     #E0C8A0;
    --syntax-number:   #E0976A;
    --syntax-comment:  #5C5678;

    /* Semantic shortcuts */
    --accent: var(--amethyst);
    --accent-hover: #B99CFE;
    --text: var(--text-primary);
    --shadow-accent: 0 0 12px rgba(167, 139, 250, 0.08);

    /* Old name aliases for JS/template compatibility */
    --forest:       var(--amethyst);
    --forest-dim:   var(--amethyst-dim);
    --forest-glow:  var(--amethyst-glow);
    --forest-subtle: var(--amethyst-subtle);
    --clay:         var(--amber);
    --clay-dim:     var(--amber-dim);
    --clay-glow:    var(--amber-glow);
    --sand:         var(--gold);
    --moss:         var(--sage);
    --river:        var(--slate);
    --river-glow:   var(--slate-glow);
    --ember:        var(--coral);
    --ember-glow:   var(--coral-glow);
    --lichen:       var(--lavender);
    --lichen-glow:  var(--lavender-glow);
    --green-bright: var(--amethyst);
    --green-dim:    var(--amethyst-dim);
    --green-glow:   var(--amethyst-glow);
    --green-subtle: var(--amethyst-subtle);
    --orange:       var(--amber);
    --orange-glow:  var(--amber-glow);
    --purple:       var(--lavender);
    --purple-glow:  var(--lavender-glow);
    --blue:         var(--slate);
    --blue-glow:    var(--slate-glow);
    --cyan:         var(--slate);
    --cyan-glow:    var(--slate-glow);
    --red:          var(--coral);
    --red-glow:     var(--coral-glow);

    /* Spacing scale (4px base) */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;

    /* Border radius scale */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 999px;

    /* Raised surface */
    --bg-raised:     #272438;

    /* Gradient tokens */
    --gradient-amethyst: linear-gradient(135deg, var(--amethyst-dim), var(--amethyst), var(--lavender));
    --gradient-warm: linear-gradient(135deg, var(--amber-dim), var(--amber), var(--gold));
    --gradient-surface: linear-gradient(180deg, var(--bg-surface) 0%, var(--bg-base) 100%);
    --gradient-glow: radial-gradient(ellipse at 50% 0%, rgba(167, 139, 250, 0.15) 0%, transparent 70%);

    /* Shadow scale */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.2), 0 1px 2px rgba(0, 0, 0, 0.15);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.25), 0 2px 4px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.3), 0 4px 8px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.35), 0 8px 16px rgba(0, 0, 0, 0.2);

    /* Card shadows with amethyst tint */
    --shadow-card: 0 2px 8px rgba(0, 0, 0, 0.2), 0 0 0 1px rgba(167, 139, 250, 0.06);
    --shadow-card-hover: 0 8px 24px rgba(0, 0, 0, 0.25), 0 0 0 1px rgba(167, 139, 250, 0.12), 0 0 20px rgba(167, 139, 250, 0.06);

    /* Colored glow shadows */
    --shadow-glow-green: 0 0 12px rgba(167, 139, 250, 0.12), 0 0 4px rgba(167, 139, 250, 0.08);
    --shadow-glow-orange: 0 0 12px rgba(224, 151, 106, 0.12), 0 0 4px rgba(224, 151, 106, 0.08);
    --shadow-glow-purple: 0 0 12px rgba(196, 168, 232, 0.12), 0 0 4px rgba(196, 168, 232, 0.08);

    /* Enhanced glow tokens */
    --amethyst-glow-strong: rgba(167, 139, 250, 0.25);
    --amethyst-glow-subtle: rgba(167, 139, 250, 0.08);

    /* Extended radius */
    --radius-2xl: 20px;

    /* Transition presets */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.2s ease;
    --transition-slow: 0.3s ease;
}

/* Theme CSS files are loaded from themes/ directory */

/* ============================================
   Scroll Progress Bar
   ============================================ */
.scroll-progress {
    position: fixed;
    top: 0;
    left: 0;
    width: 0%;
    height: 3px;
    background: linear-gradient(90deg, var(--amethyst-dim), var(--amethyst), var(--lavender));
    z-index: 9999;
    pointer-events: none;
    transition: width 0.1s linear;
    box-shadow: 0 0 12px rgba(167, 139, 250, 0.4), 0 0 4px rgba(167, 139, 250, 0.2);
}

/* ============================================
   2. Reset and Base Styles
   ============================================ */
html {
    scroll-behavior: smooth;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

::selection {
    background: rgba(167, 139, 250, 0.3);
    color: #fff;
}

body {
    font-family: 'Space Grotesk', sans-serif;
    background: var(--bg-base);
    color: var(--text-primary);
    line-height: 1.8;
    letter-spacing: 0.01em;
    min-height: 100vh;
    background-image: radial-gradient(ellipse at 20% 50%, rgba(167, 139, 250, 0.06) 0%, transparent 50%),
                      radial-gradient(ellipse at 80% 20%, rgba(196, 168, 232, 0.04) 0%, transparent 50%),
                      radial-gradient(ellipse at 50% 100%, rgba(139, 115, 222, 0.03) 0%, transparent 40%);
    background-attachment: fixed;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
    mix-blend-mode: overlay;
    opacity: 0.02;
    pointer-events: none;
    z-index: 0;
}

/* ============================================
   3. Container/Layout
   ============================================ */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--space-8);
    transition: margin-left var(--transition-slow);
}

/* ============================================
   5. Navigation (Top Nav Links)
   ============================================ */
nav.top-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-4) 0;
    border-bottom: 1px solid var(--border-subtle);
    margin-bottom: var(--space-8);
}

nav.top-nav a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color var(--transition-normal);
}

nav.top-nav a:hover {
    color: var(--green-bright);
}

/* ============================================
   Breadcrumb Navigation
   ============================================ */
.breadcrumb {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    color: var(--text-tertiary);
    margin-bottom: var(--space-2);
}
.breadcrumb a {
    color: var(--text-tertiary);
    text-decoration: none;
    padding: 0.2rem 0.5rem;
    border-radius: var(--radius-sm);
    transition: all var(--transition-normal);
}
.breadcrumb a:hover {
    color: var(--amethyst);
    background: rgba(167, 139, 250, 0.08);
}
.breadcrumb-sep {
    margin: 0 var(--space-2);
    opacity: 0.5;
}

/* ============================================
   6. Module Header Styles
   ============================================ */
.module-header {
    margin-bottom: var(--space-12);
    padding-bottom: var(--space-8);
    border-bottom: 1px solid var(--border-subtle);
}

.module-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--green-bright);
    margin-bottom: var(--space-2);
}

.module-tag {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.72rem;
    color: var(--text-tertiary);
    letter-spacing: 0.12em;
    text-transform: uppercase;
    margin-bottom: var(--space-2);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.module-tag::before {
    content: '';
    display: inline-block;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--amethyst);
    animation: tagPulse 2s ease-in-out infinite;
}

@keyframes tagPulse {
    0%, 100% { opacity: 0.5; box-shadow: 0 0 0 0 rgba(167, 139, 250, 0.3); }
    50% { opacity: 1; box-shadow: 0 0 8px 2px rgba(167, 139, 250, 0.2); }
}

.module-header h1 {
    font-size: clamp(2rem, 5vw, 2.8rem);
    font-weight: 700;
    margin-bottom: var(--space-4);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--amethyst) 50%, var(--lavender) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.module-header .description {
    color: var(--text-secondary);
    font-size: 1.1rem;
    max-width: 700px;
}

.module-desc {
    color: var(--text-secondary);
    font-size: 1.1rem;
    max-width: 700px;
}

/* ============================================
   8. Code Blocks with Syntax Highlighting
   ============================================ */
.code-block {
    background: #16132A;
    border: 1px solid rgba(167, 139, 250, 0.18);
    border-radius: var(--radius-md);
    padding: var(--space-6);
    margin: var(--space-8) 0;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.3), inset 0 1px 0 rgba(167, 139, 250, 0.06);
}

.code-block code {
    color: var(--text-primary);
}

.code-block .keyword {
    color: var(--purple);
}

.code-block .string {
    color: var(--green-bright);
}

.code-block .comment {
    color: var(--text-secondary);
    font-style: italic;
}

.code-block .func {
    color: var(--blue);
}

.code-block .type {
    color: var(--cyan);
}

.code-block .number {
    color: var(--orange);
}

pre {
    margin: 0;
    white-space: pre-wrap;
    word-wrap: break-word;
    tab-size: 4;
    -moz-tab-size: 4;
}

/* Custom scrollbars for code blocks */
pre::-webkit-scrollbar {
    height: 6px;
}

pre::-webkit-scrollbar-track {
    background: transparent;
}

pre::-webkit-scrollbar-thumb {
    background: rgba(167, 139, 250, 0.2);
    border-radius: 3px;
}

pre::-webkit-scrollbar-thumb:hover {
    background: rgba(167, 139, 250, 0.4);
}

/* Markdown-generated code blocks (pre > code) */
.lesson pre {
    position: relative;
    background: #12101E;
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-left: none;
    border-radius: var(--radius-md);
    padding: var(--space-6);
    padding-left: calc(var(--space-6) + 4px);
    margin: var(--space-8) 0;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.3), 0 0 0 1px rgba(167, 139, 250, 0.06);
    transition: box-shadow var(--transition-normal), transform var(--transition-normal);
}

.lesson pre::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, var(--amethyst), var(--amethyst-dim), var(--lavender));
    border-radius: 3px 0 0 3px;
}

.lesson pre:hover {
    box-shadow: 0 6px 24px rgba(0, 0, 0, 0.35), 0 0 24px rgba(167, 139, 250, 0.08);
    transform: translateY(-1px);
}

.code-copy-btn {
    position: absolute;
    top: var(--space-2);
    right: var(--space-2);
    background: rgba(23, 21, 36, 0.7);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    padding: 0.2rem 0.5rem;
    cursor: pointer;
    opacity: 0;
    transition: opacity var(--transition-normal), color var(--transition-normal), border-color var(--transition-normal);
}

.lesson pre:hover .code-copy-btn {
    opacity: 1;
}

.code-copy-btn:hover {
    border-color: var(--green-bright);
    color: var(--green-bright);
}

.code-copy-btn.copied {
    color: var(--green-bright);
    border-color: var(--green-bright);
}

.lesson pre code {
    background: none;
    padding: 0;
    border: none;
    border-radius: 0;
    font-size: inherit;
    color: var(--text-primary);
}

/* Code comparison layout (side-by-side labeled blocks) */
.code-compare {
    display: grid;
    grid-template-columns: 1fr 1fr;
    margin: var(--space-6) 0;
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.code-compare .code-labeled + .code-labeled {
    border-left: 1px solid var(--border-default);
}

.code-compare .code-labeled {
    border: none;
    border-radius: 0;
    margin: 0;
    min-width: 0;
    display: flex;
    flex-direction: column;
}

.code-compare .code-labeled pre {
    flex: 1;
}

.code-compare pre {
    margin: 0;
    border: none;
    border-radius: 0;
}

/* Standalone labeled code block (single, not in compare) */
.code-labeled {
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-md);
    overflow: hidden;
    margin: var(--space-6) 0;
}

.code-labeled pre {
    margin: 0;
    border: none;
    border-radius: 0;
}

/* Language label header */
.code-header {
    background: #1E1A34;
    padding: 0.45rem var(--space-4);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--amethyst);
    border-bottom: 1px solid rgba(167, 139, 250, 0.25);
}

/* Syntax highlighting (highlight.js classes using theme variables) */
.hljs { color: var(--text-primary); }
.hljs-keyword,
.hljs-selector-tag,
.hljs-built_in,
.hljs-name { color: var(--syntax-keyword); }
.hljs-string,
.hljs-attr,
.hljs-symbol,
.hljs-bullet,
.hljs-addition { color: var(--syntax-string); }
.hljs-title,
.hljs-title.function_,
.hljs-section { color: var(--syntax-function); }
.hljs-comment,
.hljs-quote,
.hljs-deletion { color: var(--syntax-comment); font-style: italic; }
.hljs-type,
.hljs-template-tag,
.hljs-class .hljs-title { color: var(--syntax-type); }
.hljs-number,
.hljs-literal,
.hljs-variable,
.hljs-template-variable,
.hljs-tag .hljs-attr { color: var(--syntax-number); }
.hljs-meta,
.hljs-doctag { color: var(--text-secondary); }
.hljs-params { color: var(--text-primary); }
.hljs-punctuation { color: var(--text-secondary); }

@media (max-width: 768px) {
    .code-compare {
        grid-template-columns: 1fr;
    }
    .code-compare .code-labeled + .code-labeled {
        border-left: none;
        border-top: 1px solid var(--border-default);
    }
}

/* Exercise jump-to box */
.exercise-jump-box {
    background: var(--bg-surface);
    border-radius: var(--radius-md);
    padding: var(--space-4) var(--space-6);
    margin: var(--space-4) 0 var(--space-8) 0;
    box-shadow: var(--shadow-xs);
}

.exercise-jump-label {
    font-weight: 600;
    margin-bottom: var(--space-3);
    color: var(--text);
}

.exercise-jump-links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2) var(--space-4);
    font-size: 0.9rem;
}

.exercise-jump-links a {
    text-decoration: none;
    transition: opacity var(--transition-normal);
}

.exercise-jump-links a:first-child {
    color: var(--green-bright);
}

.exercise-jump-links a:last-child {
    color: var(--orange);
}

.exercise-jump-links a:hover {
    opacity: 0.8;
}

/* ============================================
   10. Tips and Warnings
   ============================================ */
.tip, .warning, .info {
    padding: var(--space-5) var(--space-5) var(--space-5) var(--space-6);
    border-radius: var(--radius-md);
    margin: var(--space-8) 0;
    border-left: 4px solid;
    box-shadow: var(--shadow-sm);
}

.tip, .warning, .info {
    /* shared label style */
}

.tip::before, .warning::before, .info::before {
    display: inline-block;
    font-family: 'JetBrains Mono', monospace;
    font-weight: 700;
    font-size: 0.7rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 0.15rem 0.5rem;
    border-radius: 3px;
    margin-bottom: var(--space-3);
}

.tip {
    background: rgba(140, 198, 140, 0.10);
    border-left-color: var(--sage);
}

.tip::before {
    content: 'Tip';
    color: var(--sage);
    background: rgba(140, 198, 140, 0.12);
}

.warning {
    background: rgba(224, 96, 112, 0.10);
    border-left-color: var(--coral);
}

.warning::before {
    content: 'Warning';
    color: var(--coral);
    background: rgba(224, 96, 112, 0.12);
}

.info {
    background: rgba(124, 180, 224, 0.10);
    border-left-color: var(--slate);
}

.info::before {
    content: 'Note';
    color: var(--slate);
    background: rgba(124, 180, 224, 0.12);
}

/* ============================================
   10b. Callout Cards (Mathesis-inspired)
   ============================================ */
.callout {
    border: 1px solid var(--border-default);
    border-left: none;
    border-radius: var(--radius-lg);
    margin: var(--space-8) 0;
    overflow: hidden;
    box-shadow: var(--shadow-card);
    position: relative;
}
.callout::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: linear-gradient(180deg, var(--text-tertiary), var(--text-ghost));
    border-radius: 4px 0 0 4px;
}

.callout-header {
    padding: var(--space-3) var(--space-5);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    border-bottom: 1px solid var(--border-subtle);
}

.callout-type {
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-right: var(--space-2);
}

.callout-body {
    padding: var(--space-5);
}

.callout-body > *:last-child {
    margin-bottom: 0;
}

/* Callout: tip — sage/green */
.callout.tip::before {
    background: linear-gradient(180deg, var(--sage), rgba(140, 198, 140, 0.4));
}
.callout.tip .callout-header {
    background: rgba(140, 198, 140, 0.12);
    color: var(--sage);
}

/* Callout: warning — coral/red */
.callout.warning::before {
    background: linear-gradient(180deg, var(--coral), rgba(224, 96, 112, 0.4));
}
.callout.warning .callout-header {
    background: rgba(224, 96, 112, 0.12);
    color: var(--coral);
}

/* Callout: info — slate/blue */
.callout.info::before {
    background: linear-gradient(180deg, var(--slate), rgba(124, 180, 224, 0.4));
}
.callout.info .callout-header {
    background: rgba(124, 180, 224, 0.12);
    color: var(--slate);
}

/* Callout: definition — amethyst/purple */
.callout.definition::before {
    background: linear-gradient(180deg, var(--amethyst), rgba(167, 139, 250, 0.4));
}
.callout.definition .callout-header {
    background: rgba(167, 139, 250, 0.12);
    color: var(--amethyst);
}

/* Callout: example — amber/orange */
.callout.example::before {
    background: linear-gradient(180deg, var(--amber), rgba(224, 151, 106, 0.4));
}
.callout.example .callout-header {
    background: rgba(224, 151, 106, 0.12);
    color: var(--amber);
}

/* ============================================
   11. Exercises and Hints/Solutions
   ============================================ */
.js-required {
    color: var(--text-secondary);
    font-style: italic;
    padding: var(--space-4);
    text-align: center;
}

.exercise {
    background: var(--bg-surface);
    border: 1px solid rgba(224, 151, 106, 0.12);
    border-left: none;
    border-radius: var(--radius-lg);
    padding: var(--space-5);
    padding-left: calc(var(--space-5) + 4px);
    margin: var(--space-6) 0;
    box-shadow: var(--shadow-card);
    transition: box-shadow var(--transition-normal), transform var(--transition-normal);
    position: relative;
}

.exercise::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: linear-gradient(180deg, var(--amber), var(--gold));
    border-radius: 4px 0 0 4px;
}

.exercise:hover {
    box-shadow: var(--shadow-card-hover), 0 0 20px rgba(224, 151, 106, 0.06);
    transform: translateY(-2px);
}

/* Exercise Accordion */
.exercise-accordion {
    margin: 0;
}

.exercise-accordion summary {
    list-style: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: 0;
    color: inherit;
    user-select: none;
}

.exercise-accordion summary::-webkit-details-marker {
    display: none;
}

.exercise-accordion summary::before {
    display: none;
}

.exercise-accordion summary h4 {
    flex: 1;
    margin: 0;
    font-size: 1rem;
    font-weight: 600;
}

.exercise-type-tag {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.65rem;
    font-weight: 600;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    padding: 0.15rem 0.55rem;
    border-radius: var(--radius-full);
    background: rgba(224, 151, 106, 0.10);
    color: var(--amber);
    border: 1px solid rgba(224, 151, 106, 0.20);
    white-space: nowrap;
}

.accordion-chevron {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
    padding: 2px;
    color: var(--text-secondary);
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-sm);
    transition: transform var(--transition-normal), color var(--transition-normal), border-color var(--transition-normal);
}

.exercise-accordion summary:hover .accordion-chevron {
    color: var(--amber);
    border-color: var(--amber);
}

.exercise-accordion[open] .accordion-chevron {
    transform: rotate(90deg);
}

.exercise-body {
    padding-top: var(--space-4);
}

/* When self-rating follows a closed accordion, add breathing room */
.exercise-accordion + .self-rating {
    margin-top: var(--space-3);
    border-top: none;
}

.exercise-accordion[open] + .self-rating {
    border-top: 1px solid var(--border-subtle);
}

/* Exercise h4 outside accordion */
.exercise > h4 {
    margin-top: 0;
    margin-bottom: var(--space-3);
}

.exercise-header {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    margin-bottom: var(--space-4);
}

.exercise-header h3 {
    font-size: 1.2rem;
    color: var(--orange);
}

.exercise-icon {
    font-size: 1.5rem;
}

.exercise p {
    margin-bottom: var(--space-4);
}

.exercise-description {
    margin-bottom: var(--space-4);
    line-height: 1.65;
    color: var(--text-primary);
}

.exercise-description code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.88em;
    background: var(--bg-elevated);
    padding: 0.15em 0.4em;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-subtle);
    color: var(--amber);
}

.exercise pre {
    white-space: pre;
    overflow-x: auto;
    background: var(--bg-elevated);
    border-radius: 6px;
    padding: var(--space-3) var(--space-4);
    margin: var(--space-2) 0;
}

/* Function signature block */
.function-signature {
    margin: var(--space-4) 0;
    border: 1px solid rgba(224, 151, 106, 0.25);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.function-signature-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--amber);
    background: rgba(224, 151, 106, 0.08);
    padding: var(--space-2) var(--space-4);
    border-bottom: 1px solid rgba(224, 151, 106, 0.15);
}

.function-signature pre {
    margin: 0;
    padding: var(--space-3) var(--space-4);
    background: var(--bg-elevated);
    font-size: 0.92rem;
    line-height: 1.5;
    color: var(--text-primary);
    border-radius: 0;
}

/* Test cases */
.expected {
    margin-top: var(--space-5);
}

.expected-title {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-secondary);
    margin-bottom: var(--space-3);
}

.expected pre {
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: var(--space-4) var(--space-5);
    font-size: 0.92rem;
    line-height: 1.6;
    color: var(--text-primary);
}

.test-case-row {
    background: var(--bg-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: var(--space-3);
}

.test-case-row:last-child {
    margin-bottom: 0;
}

.test-case-section {
    padding: var(--space-3) var(--space-4);
}

.test-case-section + .test-case-section {
    border-top: 1px dashed var(--border-subtle);
}

.test-case-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.65rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--text-secondary);
    display: block;
    margin-bottom: var(--space-1);
}

.test-case-section pre {
    margin: 0;
    padding: 0;
    background: transparent;
    border: none;
    font-size: 0.9rem;
    line-height: 1.5;
    border-radius: 0;
    box-shadow: none;
    position: static;
}

.test-case-section pre::before {
    display: none;
}

.test-case-section pre:hover {
    box-shadow: none;
    transform: none;
}

.hint, .solution {
    margin-top: var(--space-4);
}

.hint-toggle, .solution-toggle {
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    border-radius: 6px;
    padding: var(--space-3) var(--space-4);
    color: var(--text-primary);
    cursor: pointer;
    font-size: 0.9rem;
    transition: all var(--transition-normal);
    width: 100%;
    text-align: left;
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.hint-toggle:hover, .solution-toggle:hover {
    border-color: var(--green-dim);
}

.hint-content, .solution-content {
    display: none;
    padding: var(--space-4);
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    border-top: none;
    border-radius: 0 0 6px 6px;
}

.hint-content.show, .solution-content.show {
    display: block;
}

/* Details/Summary collapsible elements */
details {
    margin: var(--space-3) 0;
}

details summary {
    cursor: pointer;
    color: var(--cyan);
    font-weight: 500;
    padding: var(--space-2) 0;
    user-select: none;
    list-style: none;
    transition: color var(--transition-normal);
}

details summary::-webkit-details-marker {
    display: none;
}

details summary::before {
    content: "\25B6 ";
    font-size: 0.8em;
    margin-right: 0.25rem;
    display: inline-block;
    transition: transform var(--transition-normal);
}

details[open] summary::before {
    content: "\25B6 ";
    transform: rotate(90deg);
}

details summary:hover {
    color: var(--green-bright);
}

details[open] summary {
    margin-bottom: var(--space-2);
}

details .hint-content {
    display: block;
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    border-left: 2px solid var(--orange);
    border-radius: var(--radius-sm);
    padding: var(--space-4);
    margin-top: var(--space-2);
    box-shadow: var(--shadow-xs);
}

details .hint-content pre {
    white-space: pre;
    overflow-x: auto;
}

/* ============================================
   12. Navigation Buttons
   ============================================ */
.nav-buttons {
    display: flex;
    justify-content: space-between;
    margin-top: var(--space-16);
    padding-top: var(--space-8);
    border-top: none;
    position: relative;
}

.nav-buttons::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--amethyst-dim), transparent);
}

.nav-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-lg);
    color: var(--text-primary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-card);
}

.nav-btn:hover {
    border-color: rgba(167, 139, 250, 0.3);
    box-shadow: var(--shadow-card-hover);
    transform: translateY(-2px);
}

.nav-btn.primary {
    background: var(--green-bright);
    color: var(--bg-base);
    border-color: var(--green-bright);
}

.nav-btn.primary:hover {
    background: var(--accent-hover);
    box-shadow: var(--shadow-accent);
}

/* ============================================
   13. Lists and Inline Code
   ============================================ */
ul, ol {
    margin: var(--space-4) 0 var(--space-6) var(--space-8);
}

li {
    margin-bottom: var(--space-3);
}

.lesson li > strong:first-child {
    color: var(--cyan);
}

code:not(.code-block code):not(pre code) {
    background: rgba(167, 139, 250, 0.08);
    padding: 0.2rem 0.5rem;
    border-radius: var(--radius-sm);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    color: var(--amethyst);
    border: 1px solid rgba(167, 139, 250, 0.18);
}

.lesson {
    font-size: 1.05rem;
}

h1 { line-height: 1.15; }
h2 { line-height: 1.2; }
h3, h4 { line-height: 1.3; }

h2, h3, h4 {
    margin-top: var(--space-8);
    margin-bottom: var(--space-4);
}

.lesson h3 {
    margin-top: var(--space-12);
}

h2 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.lesson h2 {
    font-weight: 600;
    font-size: 1.5rem;
    margin-top: 4rem;
    padding-top: 2.5rem;
    border-top: none;
    background-image: linear-gradient(90deg, var(--amethyst-dim), rgba(167, 139, 250, 0.15), transparent);
    background-size: 100% 1px;
    background-repeat: no-repeat;
    background-position: top;
}

/* More breathing room AFTER code blocks than before */
.lesson pre + p,
.lesson .code-block + p,
.lesson .code-compare + p,
.lesson .code-labeled + p {
    margin-top: 2rem;
}

/* Generous space after exercises before next concept */
.inline-exercises + h2 {
    margin-top: 4rem;
}

.lesson h2:first-child {
    margin-top: 0;
    padding-top: 0;
    border-top: none;
}

.lesson h2::before {
    content: '';
    display: inline-block;
    width: 4px;
    height: 1.2em;
    background: linear-gradient(180deg, var(--amethyst), var(--amethyst-dim));
    border-radius: 2px;
    margin-right: 0.6rem;
    vertical-align: text-bottom;
}

.lesson blockquote {
    background: rgba(224, 151, 106, 0.08);
    border-left: none;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding: var(--space-4) var(--space-5);
    padding-left: calc(var(--space-5) + 4px);
    margin: var(--space-8) 0;
    color: var(--text-secondary);
    box-shadow: var(--shadow-xs);
    position: relative;
}

.lesson blockquote::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    border-radius: 4px 0 0 4px;
    background: linear-gradient(180deg, var(--amber), var(--gold));
}

.lesson blockquote p:last-child {
    margin-bottom: 0;
}

.lesson blockquote strong {
    color: var(--text-primary);
}

.lesson blockquote code {
    color: var(--purple);
}

/* Lesson tables */
.lesson table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin: var(--space-6) 0;
    font-size: 0.9rem;
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.lesson table th {
    background: rgba(167, 139, 250, 0.08);
    font-weight: 600;
    font-size: 0.8rem;
    color: var(--amethyst);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    text-align: left;
    padding: var(--space-3) var(--space-4);
    border-bottom: 1px solid var(--border-subtle);
}

.lesson table td {
    padding: var(--space-3) var(--space-4);
    border-bottom: 1px solid var(--border-subtle);
    color: var(--text-primary);
}

.lesson table tr:last-child td {
    border-bottom: none;
}

.lesson table tr:nth-child(even) td {
    background: rgba(255, 255, 255, 0.02);
}

.lesson table tr:hover td {
    background: rgba(167, 139, 250, 0.05);
    transition: background var(--transition-fast);
}

.lesson table code {
    font-size: 0.82em;
}

h3 {
    font-size: 1.2rem;
}

.lesson h3 {
    font-size: 1.2rem;
    position: relative;
    padding-left: 0.8rem;
}

.lesson h3::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.15em;
    width: 3px;
    height: 1em;
    background: var(--amethyst);
    border-radius: 2px;
    opacity: 0.6;
}

p {
    margin-bottom: var(--space-4);
}

a {
    color: var(--accent);
    text-decoration: none;
    transition: color var(--transition-normal);
}

a:hover {
    color: var(--accent-hover);
}

.lesson a {
    text-decoration: underline;
    text-decoration-color: rgba(167, 139, 250, 0.3);
    text-underline-offset: 2px;
    text-decoration-thickness: 1px;
    transition: color var(--transition-normal), text-decoration-color var(--transition-normal);
}

.lesson a:hover {
    text-decoration-color: var(--accent-hover);
}

/* ============================================
   14. Theme Toggle Button
   ============================================ */
.theme-toggle {
    width: 44px;
    height: 44px;
    background: rgba(23, 21, 36, 0.6);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(167, 139, 250, 0.1);
    border-radius: var(--radius-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: var(--text-primary);
    transition: all var(--transition-normal);
}

.theme-picker {
    position: fixed;
    top: var(--space-4);
    right: var(--space-4);
    z-index: 101;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-2);
}


.theme-actions {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.focus-toggle {
    border: 1px solid var(--border-default);
    background: var(--bg-surface);
    color: var(--text-secondary);
    border-radius: var(--radius-full);
    padding: 0.35rem 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    min-width: 180px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.show-timer-toggle {
    border: 1px solid var(--border-default);
    background: var(--bg-surface);
    color: var(--text-secondary);
    border-radius: var(--radius-full);
    padding: 0.35rem 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    min-width: 180px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.show-timer-toggle:hover {
    border-color: var(--orange);
    color: var(--orange);
}

.focus-toggle-slot {
    margin: var(--space-3) 0 var(--space-8);
    display: flex;
    justify-content: flex-start;
}

.focus-toggle:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.focus-toggle.active {
    background: var(--accent);
    color: var(--bg-base);
    border-color: var(--accent);
    box-shadow: var(--shadow-glow-green);
}

/* ============================================
   20. Focus Mode
   ============================================ */
body.focus-mode .sidebar,
body.focus-mode .sidebar-toggle,
body.focus-mode .sidebar-backdrop {
    display: none !important;
}

body.focus-mode nav,
body.focus-mode .breadcrumb {
    display: none !important;
}

body.focus-mode .container > * {
    opacity: 0.45;
    transition: opacity var(--transition-normal);
}

body.focus-mode .lesson,
body.focus-mode .focus-content,
body.focus-mode .session-complete {
    opacity: 1;
}

body.focus-mode.dp-in-session #dp-config {
    opacity: 0.45;
}

body.focus-mode .session-timer,
body.focus-mode .floating-session-timer,
body.focus-mode .focus-toggle {
    opacity: 1;
}

body.focus-mode .theme-toggle {
    opacity: 0.3;
}

body.focus-mode .code-compare {
    display: block;
}

.theme-toggle:hover {
    border-color: rgba(167, 139, 250, 0.3);
    box-shadow: 0 0 12px rgba(167, 139, 250, 0.15);
}

.theme-toggle .icon-sun {
    display: none;
}

.theme-toggle .icon-moon {
    display: block;
}

[data-theme="light"] .theme-toggle .icon-sun {
    display: block;
}

[data-theme="light"] .theme-toggle .icon-moon {
    display: none;
}

/* ============================================
   14b. Session Timer
   ============================================ */
.session-timer,
.floating-session-timer {
    background: rgba(23, 21, 36, 0.9);
    backdrop-filter: blur(16px) saturate(1.3);
    -webkit-backdrop-filter: blur(16px) saturate(1.3);
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-xl);
    padding: var(--space-4) var(--space-5);
    box-shadow: var(--shadow-lg), 0 0 20px rgba(167, 139, 250, 0.05);
}

.floating-session-timer {
    position: fixed;
    right: var(--space-4);
    bottom: var(--space-4);
    width: min(320px, calc(100% - 2rem));
    z-index: 102;
}

.session-timer-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-3);
}

.session-title {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.session-countdown {
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.1rem;
    color: var(--orange);
}

.session-progress {
    background: var(--bg-elevated);
    border-radius: var(--radius-full);
    height: 6px;
    overflow: hidden;
}

.session-progress-bar {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--amethyst), var(--amethyst-dim));
    transition: width var(--transition-slow);
}

.session-meta {
    margin-top: 0.6rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.session-message {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-top: var(--space-1);
    min-height: 1.2em;
    opacity: 0.7;
}

.session-message:empty {
    display: none;
}

.session-controls {
    display: flex;
    gap: var(--space-2);
    margin-top: var(--space-3);
}

.session-duration-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-3);
    margin-top: var(--space-3);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.session-duration-select {
    background: var(--bg-surface);
    color: var(--text-primary);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-full);
    padding: 0.35rem 0.75rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    cursor: pointer;
}

.session-control-btn {
    background: transparent;
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
    padding: 0.35rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.session-control-btn:hover {
    border-color: var(--orange);
    color: var(--orange);
}

.session-control-btn.danger:hover {
    border-color: var(--red);
    color: var(--red);
}

.session-drag-handle {
    cursor: move;
    user-select: none;
}

/* Timer visual enhancements */
@keyframes timer-complete-flash {
    0% {
        box-shadow: 0 0 0 0 var(--amethyst);
        border-color: var(--amethyst);
    }
    50% {
        box-shadow: 0 0 30px 10px rgba(167, 139, 250, 0.2);
        border-color: var(--amethyst);
        transform: scale(1.02);
    }
    100% {
        box-shadow: 0 0 0 0 rgba(167, 139, 250, 0.1);
        border-color: var(--border-default);
        transform: scale(1);
    }
}

@keyframes timer-pulse {
    0%, 100% {
        box-shadow: var(--shadow-lg), 0 0 0 rgba(224, 151, 106, 0.1);
    }
    50% {
        box-shadow: var(--shadow-lg), 0 0 16px rgba(224, 151, 106, 0.2);
    }
}

.timer-complete {
    animation: timer-complete-flash 1s ease-out;
}

.session-timer:not([hidden]),
.floating-session-timer {
    animation: timer-pulse 3s ease-in-out infinite;
}

/* ============================================
   15. Sidebar Styles
   ============================================ */
.sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: 280px;
    height: 100vh;
    background: rgba(23, 21, 36, 0.85);
    backdrop-filter: blur(20px) saturate(1.3);
    -webkit-backdrop-filter: blur(20px) saturate(1.3);
    border-right: 1px solid rgba(167, 139, 250, 0.12);
    overflow-y: auto;
    padding: 0 0 var(--space-4);
    z-index: 100;
    transform: translateX(-100%);
    transition: transform var(--transition-slow);
    box-shadow: 4px 0 24px rgba(0, 0, 0, 0.2);
    scrollbar-width: thin;
    scrollbar-color: rgba(167, 139, 250, 0.15) transparent;
}

.sidebar::-webkit-scrollbar {
    width: 4px;
}

.sidebar::-webkit-scrollbar-track {
    background: transparent;
}

.sidebar::-webkit-scrollbar-thumb {
    background: rgba(167, 139, 250, 0.15);
    border-radius: 2px;
}

.sidebar::-webkit-scrollbar-thumb:hover {
    background: rgba(167, 139, 250, 0.3);
}

.sidebar.open {
    transform: translateX(0);
}


.sidebar-toggle {
    position: fixed;
    left: var(--space-4);
    top: var(--space-2);
    width: 40px;
    height: 40px;
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: 6px;
    cursor: pointer;
    z-index: 101;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: var(--text-primary);
    transition: all var(--transition-slow);
}

.sidebar-toggle:hover {
    border-color: var(--amethyst);
}

/* When sidebar is open (mobile), toggle merges into the header bar */
body.sidebar-open .sidebar-toggle {
    left: 0;
    top: 0;
    width: 3rem;
    height: 48px;
    background: transparent;
    border: none;
    border-right: 1px solid var(--border-subtle);
    border-radius: 0;
}

body.sidebar-open .sidebar-toggle:hover {
    background: var(--bg-elevated);
}


.sidebar-header {
    padding: 0 var(--space-4) 0 3.5rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    border-bottom: 1px solid rgba(167, 139, 250, 0.15);
    margin-bottom: var(--space-2);
    min-height: 48px;
    display: flex;
    align-items: center;
}

.sidebar-header a {
    color: var(--green-bright);
    text-decoration: none;
    transition: color var(--transition-normal);
}

.sidebar-header a:hover {
    color: var(--text-primary);
}

.sidebar-content {
    /* Container for module list */
}

.sidebar-sections {
    /* Nested sections under active module */
    margin-left: var(--space-6);
    padding-left: var(--space-3);
    border-left: 1px solid var(--border-subtle);
    margin-bottom: var(--space-2);
}

.sidebar-section-link {
    display: block;
    padding: 0.4rem var(--space-3);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.75rem;
    transition: all var(--transition-normal);
    border-radius: var(--radius-sm);
}

.sidebar-section-link:hover {
    color: var(--cyan);
    background: var(--bg-elevated);
}

.sidebar-section-link.active {
    color: var(--cyan);
    font-weight: 500;
    border-left: 2px solid var(--accent);
}

/* Sidebar chapter/section hierarchy (split modules) */
.sidebar-chapter {
    margin-bottom: var(--space-1);
}

.sidebar-chapter-title {
    display: flex;
    align-items: center;
    padding: var(--space-2) var(--space-4);
    font-size: 0.85rem;
    color: var(--text-secondary);
    text-decoration: none;
    border-left: 3px solid transparent;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    transition: all var(--transition-normal);
}

.sidebar-chapter-title:hover {
    color: var(--green-bright);
    background: var(--bg-elevated);
}

.sidebar-chapter-title.active {
    color: var(--green-bright);
    background: rgba(167, 139, 250, 0.08);
    border-left-color: var(--accent);
}

.sidebar-chapter-sections {
    margin-left: var(--space-6);
    padding-left: var(--space-3);
    border-left: 1px solid var(--border-subtle);
    margin-bottom: var(--space-2);
}

.sidebar-section-num {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.68rem;
    opacity: 0.6;
    margin-right: var(--space-2);
    flex-shrink: 0;
}

/* H2 headings within an active section page */
.sidebar-h2-link {
    display: block;
    padding: 0.25rem var(--space-2) 0.25rem 2rem;
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.72rem;
    transition: color var(--transition-normal);
}

.sidebar-h2-link:hover {
    color: var(--cyan);
}

.sidebar::after {
    content: '';
    position: sticky;
    bottom: 0;
    display: block;
    height: 2rem;
    background: linear-gradient(transparent, var(--bg-surface));
    pointer-events: none;
}

.sidebar-link {
    display: flex;
    align-items: center;
    padding: var(--space-2) var(--space-4);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    transition: all var(--transition-normal);
    border-left: 3px solid transparent;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.sidebar-link:hover {
    color: var(--green-bright);
    background: var(--bg-elevated);
}

.sidebar-link.active {
    color: var(--green-bright);
    background: rgba(167, 139, 250, 0.08);
    border-left-color: var(--accent);
}

.sidebar-module-num {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    opacity: 0.7;
    margin-right: var(--space-2);
}

.sidebar-link.sidebar-project-link {
    color: var(--teal);
}

.sidebar-link.sidebar-project-link:hover {
    color: var(--teal);
}

.sidebar-link.sidebar-project-link.active {
    color: var(--teal);
    border-left-color: var(--teal);
}

.sidebar-link.completed::after {
    content: '';
    width: 8px;
    height: 8px;
    background: var(--green-bright);
    border-radius: 50%;
    margin-left: auto;
    flex-shrink: 0;
}

/* Sidebar completion dots */
.sidebar-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--bg-muted);
    flex-shrink: 0;
    margin-left: auto;
}
.sidebar-dot.complete {
    background: var(--forest);
}
.sidebar-dot.started {
    background: var(--clay);
}
.sidebar-link.completed .sidebar-dot {
    display: none;
}

/* Add top padding when sidebar toggle is present */
.has-sidebar .container {
    padding-top: var(--space-16);
}

/* Hide the old inline nav — sidebar replaces it */
.has-sidebar .container > nav:first-child {
    display: none;
}

/* Desktop: sidebar always visible */
@media (min-width: 901px) {
    .sidebar {
        transform: translateX(0);
    }

    .sidebar-toggle {
        display: none;
    }

    .has-sidebar .container {
        margin-left: 300px;
        padding-top: var(--space-8);
    }
}

/* Ultrawide: center content in the space right of sidebar */
@media (min-width: 1500px) {
    .has-sidebar .container {
        margin-left: calc(50vw - 310px);
    }
}

/* Mobile: collapsible overlay */
@media (max-width: 900px) {
    .sidebar {
        width: 100%;
        max-width: 320px;
    }

    body.sidebar-open .container {
        margin-left: 0;
    }

    .sidebar-backdrop {
        display: none;
        position: fixed;
        inset: 0;
        background: rgba(0, 0, 0, 0.6);
        backdrop-filter: blur(4px);
        z-index: 99;
    }

    body.sidebar-open .sidebar-backdrop {
        display: block;
    }
}

/* ============================================
   17. Footer
   ============================================ */
footer {
    border-top: 1px solid var(--border-subtle);
    padding: var(--space-8) 0;
    margin-top: var(--space-16);
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* ============================================
   18. Visual Box, Quote Box, Concept Links
   ============================================ */
.visual-box {
    background: rgba(124, 180, 224, 0.05);
    border: 1px solid rgba(124, 180, 224, 0.15);
    border-radius: var(--radius-md);
    padding: var(--space-8);
    margin: var(--space-6) 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
}

.concept-link {
    font-size: 0.75rem;
    text-decoration: none;
    transition: all var(--transition-normal);
}

.concept-link:hover {
    text-decoration: underline;
    opacity: 1 !important;
}

/* ============================================
   19. Responsive Adjustments
   ============================================ */
/* ============================================
   Exercise Progress Tracking
   ============================================ */
.exercise-completed {
    position: relative;
}

.exercise-completed::before {
    background: linear-gradient(180deg, var(--sage), var(--amethyst-dim));
}

.exercise-completed::after {
    content: '\2713';
    position: absolute;
    top: var(--space-4);
    right: var(--space-4);
    width: 24px;
    height: 24px;
    background: var(--gradient-amethyst);
    color: #fff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 700;
    box-shadow: 0 0 12px rgba(167, 139, 250, 0.3);
}

.self-rating {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-top: var(--space-4);
    padding-top: var(--space-3);
    border-top: 1px solid var(--border-subtle);
}

.self-rating-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    white-space: nowrap;
}

.rating-btn {
    background: transparent;
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
    padding: 0.35rem 0.85rem;
    border-radius: var(--radius-full);
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.rating-btn:hover {
    border-color: var(--text);
    color: var(--text);
}

.rating-btn.active.got-it {
    background: var(--green-bright);
    border-color: var(--green-bright);
    color: var(--bg-base);
    font-weight: 600;
    box-shadow: 0 0 16px rgba(140, 198, 140, 0.3);
    transform: scale(1.05);
}

.rating-btn.active.struggled {
    background: var(--orange);
    border-color: var(--orange);
    color: var(--bg-base);
    font-weight: 600;
    box-shadow: 0 0 16px rgba(224, 151, 106, 0.3);
    transform: scale(1.05);
}

.rating-btn.active.peeked {
    background: var(--purple);
    border-color: var(--purple);
    color: white;
    font-weight: 600;
    box-shadow: 0 0 16px rgba(196, 168, 232, 0.3);
    transform: scale(1.05);
}

/* Dashboard exercise progress */
.exercise-progress-inline {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-family: 'JetBrains Mono', monospace;
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.exercise-progress-bar {
    width: 60px;
    height: 4px;
    background: var(--bg-muted);
    border-radius: 2px;
    overflow: hidden;
    display: inline-block;
}

.exercise-progress-fill {
    height: 100%;
    background: var(--green-bright);
    border-radius: 2px;
    transition: width var(--transition-slow);
}

/* ============================================
   Solution Annotations
   ============================================ */
.solution-annotations {
    margin-top: var(--space-4);
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.annotation {
    display: flex;
    align-items: flex-start;
    gap: 0.6rem;
    padding: var(--space-2) var(--space-3);
    border-radius: 6px;
    background: var(--bg-elevated);
    border-left: 3px solid var(--text-secondary);
    font-size: 0.85rem;
}

.annotation-badge {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    font-weight: 700;
    padding: 0.15rem 0.4rem;
    border-radius: 3px;
    background: var(--bg-muted);
    white-space: nowrap;
    flex-shrink: 0;
    margin-top: 0.1rem;
}

.annotation-body {
    display: flex;
    flex-direction: column;
    gap: 0.15rem;
}

.annotation-body strong {
    font-size: 0.8rem;
}

.annotation-body span {
    color: var(--text-secondary);
    font-size: 0.8rem;
}

.ann-idiom {
    border-left-color: var(--cyan);
}
.ann-idiom .annotation-badge {
    color: var(--cyan);
}

.ann-complexity {
    border-left-color: var(--orange);
}
.ann-complexity .annotation-badge {
    color: var(--orange);
}

.ann-gotcha {
    border-left-color: var(--red);
}
.ann-gotcha .annotation-badge {
    color: var(--red);
}

.ann-alternative {
    border-left-color: var(--purple);
}
.ann-alternative .annotation-badge {
    color: var(--purple);
}

.ann-stdlib {
    border-left-color: var(--green-bright);
}
.ann-stdlib .annotation-badge {
    color: var(--green-bright);
}

.ann-pattern {
    border-left-color: var(--blue);
}
.ann-pattern .annotation-badge {
    color: var(--blue);
}

@media (max-width: 768px) {
    .container {
        padding: var(--space-4);
    }

    .module-header h1 {
        font-size: 1.75rem;
    }

    .module-header .description,
    .module-desc {
        font-size: 0.95rem;
    }

    .nav-buttons {
        flex-direction: column;
        gap: var(--space-4);
    }

    .nav-btn {
        justify-content: center;
    }

    .theme-picker {
        top: var(--space-2);
        right: var(--space-2);
    }

    .theme-toggle {
        width: 36px;
        height: 36px;
        font-size: 1.1rem;
    }

    .focus-toggle,
    .show-timer-toggle {
        min-width: 140px;
        font-size: 0.7rem;
        padding: 0.3rem 0.7rem;
    }

    /* Exercise cards */
    .exercise {
        padding: var(--space-5);
        margin: var(--space-5) 0;
    }

    .exercise-header h3 {
        font-size: 1.05rem;
    }

    /* Session timer */
    .session-timer {
        padding: var(--space-3) var(--space-4);
    }

    .floating-session-timer {
        width: min(260px, calc(100% - 1rem));
        right: var(--space-2);
        bottom: var(--space-2);
        padding: 0.6rem 0.75rem;
        border-radius: var(--radius-md);
    }

    .floating-session-timer .session-title {
        font-size: 0.65rem;
        letter-spacing: 0.5px;
    }

    .floating-session-timer .session-countdown {
        font-size: 0.85rem;
    }

    .floating-session-timer .session-meta {
        font-size: 0.7rem;
        margin-top: 0.4rem;
    }

    .floating-session-timer .session-controls {
        gap: var(--space-1);
        margin-top: var(--space-2);
        flex-wrap: wrap;
    }

    .floating-session-timer .session-control-btn {
        padding: 0.25rem 0.55rem;
        font-size: 0.65rem;
    }

    .floating-session-timer .session-duration-row {
        margin-top: var(--space-2);
        font-size: 0.65rem;
    }

    .floating-session-timer .session-duration-select {
        padding: 0.2rem 0.5rem;
        font-size: 0.65rem;
    }

    .floating-session-timer .session-timer-header {
        margin: -0.6rem -0.75rem 0.4rem -0.75rem;
        padding: 0.4rem 0.75rem;
    }

    .session-title {
        font-size: 0.75rem;
    }

    .session-countdown {
        font-size: 0.95rem;
    }

    /* Session config */
    .session-config {
        padding: var(--space-4);
    }

    .session-config-label {
        min-width: auto;
        font-size: 0.8rem;
    }

    .session-stat {
        padding: var(--space-3) var(--space-4);
        min-width: 80px;
    }

    .session-stat-value {
        font-size: 1.2rem;
    }

    .session-complete {
        padding: var(--space-5);
    }

    /* Flashcards */
    .flashcard,
    .flashcard-inner,
    .flashcard-front,
    .flashcard-back {
        min-height: 200px;
    }

    .flashcard-front,
    .flashcard-back {
        padding: var(--space-5);
    }

    /* Module list items */
    .module-item {
        gap: var(--space-2);
        padding: var(--space-3);
    }

    .module-link {
        gap: var(--space-2);
    }

    .module-num {
        min-width: auto;
        font-size: 0.7rem;
    }

    /* Code blocks */
    .lesson pre,
    .code-block {
        padding: var(--space-4);
        font-size: 0.82rem;
    }

    /* Visual box */
    .visual-box {
        padding: var(--space-5);
        font-size: 0.82rem;
    }

    /* Self-rating buttons */
    .self-rating {
        flex-wrap: wrap;
    }

    .rating-btn {
        padding: 0.4rem 0.75rem;
        font-size: 0.75rem;
        min-height: 44px;
        display: flex;
        align-items: center;
    }

    /* Session options — touch targets */
    .session-option {
        padding: 0.5rem 0.9rem;
        min-height: 44px;
        display: flex;
        align-items: center;
    }

    /* Module list — single column on mobile */
    .module-list {
        grid-template-columns: 1fr;
    }

    /* Quick buttons */
    .quick-btn {
        padding: var(--space-3) var(--space-4);
    }

    /* Dashboard */
    .dashboard-header {
        margin: var(--space-4) 0 var(--space-6);
    }

    .stats-strip {
        gap: 0.35rem;
    }

    .stat-chip {
        font-size: 0.7rem;
        padding: 0.25rem 0.65rem;
    }

    .stats-detail-content .stat-value {
        font-size: 1.2rem;
    }

    .stat-value {
        font-size: 1.2rem;
    }

    /* Data actions */
    .data-actions {
        gap: var(--space-2);
    }

    .data-btn {
        font-size: 0.75rem;
        padding: 0.4rem 0.75rem;
    }

    /* Session nav buttons */
    .session-nav-btns {
        flex-wrap: wrap;
    }

    .session-next-btn,
    .session-skip-btn {
        font-size: 0.82rem;
        padding: var(--space-2) var(--space-5);
    }
}

/* ============================================================
   Streak Section & Activity Heatmap
   ============================================================ */
.activity-heatmap {
    overflow-x: auto;
    padding: var(--space-2) 0;
}

/* ============================================================
   Flashcard Styles
   ============================================================ */
.flashcard {
    perspective: 1000px;
    cursor: pointer;
    min-height: 250px;
    box-shadow: var(--shadow-sm);
}

.flashcard-inner {
    position: relative;
    width: 100%;
    min-height: 250px;
    transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    transform-style: preserve-3d;
}

.flashcard.flipped .flashcard-inner {
    transform: rotateY(180deg);
}

.flashcard-front,
.flashcard-back {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    min-height: 250px;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.12);
    border-radius: var(--radius-xl);
    padding: var(--space-8);
    display: flex;
    align-items: center;
    justify-content: center;
    box-sizing: border-box;
    box-shadow: var(--shadow-card);
    overflow: hidden;
}

.flashcard-front::before,
.flashcard-back::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 50% 0%, rgba(167, 139, 250, 0.06) 0%, transparent 60%);
    pointer-events: none;
}

.flashcard-front {
    border-top: 3px solid var(--amethyst);
}

.flashcard-back {
    transform: rotateY(180deg);
    border-top: 3px solid var(--amber);
}

.flashcard:hover .flashcard-front,
.flashcard:hover .flashcard-back {
    box-shadow: var(--shadow-card-hover);
}

.flashcard-front code,
.flashcard-back code {
    background: var(--bg-elevated);
    padding: 0.15em 0.4em;
    border-radius: var(--radius-sm);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9em;
    color: var(--green-bright);
}

.fc-card-content {
    font-size: 1.1rem;
    line-height: 1.6;
}
.flashcard-back .fc-card-content {
    font-size: 1rem;
}
.fc-actions {
    display: flex;
    gap: var(--space-4);
    justify-content: center;
    margin-top: var(--space-6);
}
.fc-action-btn {
    flex: 1;
}
.fc-rating {
    display: none;
    gap: var(--space-4);
    justify-content: center;
    margin-top: var(--space-4);
}
.fc-rate-btn {
    flex: 1;
}
.fc-rate-didnt {
    border-color: var(--red);
    color: var(--red);
}
.fc-rate-partial {
    border-color: var(--orange);
    color: var(--orange);
}
.fc-rate-knew {
    border-color: var(--green-bright);
    color: var(--green-bright);
}
.fc-keyboard-hint {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.8rem;
    margin-top: var(--space-4);
}

.fc-keyboard-hint kbd {
    background: var(--bg-muted);
    border: 1px solid var(--border-default);
    border-bottom: 3px solid var(--border-strong);
    border-radius: var(--radius-sm);
    padding: 0.15em 0.5em;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}

/* ============================================================
   Shared Button Styles (Quick Buttons, Option Buttons)
   ============================================================ */
.quick-btn {
    padding: var(--space-4) var(--space-6);
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    text-align: center;
    text-decoration: none;
    color: var(--text);
    transition: all var(--transition-normal);
    font-family: 'JetBrains Mono', monospace;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 0.35rem;
    cursor: pointer;
}

.quick-btn:hover {
    border-color: var(--accent);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

.quick-btn.primary {
    background: var(--green-bright);
    border-color: var(--green-bright);
    color: var(--bg-base);
    font-weight: 700;
}

.quick-btn.primary:hover {
    background: var(--accent-hover);
}



/* ============================================================
   Analytics Dashboard Styles
   ============================================================ */
.strength-bar {
    height: 8px;
    border-radius: var(--radius-sm);
    background: var(--bg-muted);
    overflow: hidden;
}

.strength-fill {
    height: 100%;
    border-radius: var(--radius-sm);
}

.analytics-drill-btn {
    display: inline-block;
    font-size: 0.75rem;
    padding: 0.2rem 0.6rem;
    border: 1px solid var(--orange);
    border-radius: var(--radius-sm);
    color: var(--orange);
    text-decoration: none;
    font-family: 'JetBrains Mono', monospace;
    transition: background var(--transition-normal), color var(--transition-normal);
    white-space: nowrap;
}

.analytics-drill-btn:hover {
    background: var(--orange);
    color: var(--bg-base);
}

/* ── Analytics Dashboard — Health Cards ── */
.health-row {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    margin: 2rem 0;
}
.stat-card {
    background: var(--bg-surface);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    border: 1px solid rgba(167, 139, 250, 0.1);
    text-align: center;
    box-shadow: var(--shadow-card);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}
.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--gradient-amethyst);
}
.stat-card::after {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 50% 0%, rgba(167, 139, 250, 0.06) 0%, transparent 60%);
    pointer-events: none;
}
.stat-card:hover {
    box-shadow: var(--shadow-card-hover);
    transform: translateY(-2px);
}
.stat-card .stat-value {
    font-size: 2rem;
    font-weight: 700;
    font-family: 'JetBrains Mono', monospace;
}
.stat-sub {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 0.15rem;
}
.sparkline-wrap { margin-top: 0.5rem; display: flex; justify-content: center; }

/* ── Analytics: Module Health Grid ── */
.module-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(56px, 1fr));
    gap: 0.5rem;
    margin: 1.5rem 0;
}
.mgrid-cell {
    aspect-ratio: 1;
    border-radius: var(--radius-md);
    position: relative;
    cursor: pointer;
    transition: transform var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'JetBrains Mono', monospace;
    font-weight: 600;
    font-size: 0.8rem;
    text-decoration: none;
}
.mgrid-cell:hover { transform: scale(1.12); z-index: 102; }
.mgrid-label {
    background: rgba(0,0,0,0.35);
    color: #fff;
    padding: 0.1rem 0.35rem;
    border-radius: 3px;
    font-size: 0.7rem;
    line-height: 1;
}
.mgrid-tooltip {
    display: none;
    position: absolute;
    bottom: calc(100% + 8px);
    left: 50%;
    transform: translateX(-50%);
    background: var(--bg-base);
    color: var(--text-primary);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    padding: 0.5rem 0.75rem;
    white-space: nowrap;
    font-size: 0.75rem;
    font-weight: 400;
    pointer-events: none;
    z-index: 10;
    box-shadow: var(--shadow-md);
}
.mgrid-tooltip::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 5px solid transparent;
    border-top-color: var(--border-default);
}
.mgrid-cell:hover .mgrid-tooltip { display: block; }

/* ── Analytics: Action Items ── */
.action-row { margin: 1.5rem 0; }
.action-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.1);
    border-radius: var(--radius-lg);
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    box-shadow: var(--shadow-xs);
    transition: all var(--transition-normal);
}
.action-item:hover {
    box-shadow: var(--shadow-sm);
    border-color: rgba(167, 139, 250, 0.2);
}
.action-icon {
    font-size: 1.1rem;
    min-width: 1.5rem;
    text-align: center;
}
.action-text { flex: 1; }
.action-link {
    color: var(--cyan);
    text-decoration: none;
    font-weight: 500;
    white-space: nowrap;
}
.action-link:hover { text-decoration: underline; }

/* ── Analytics: Detail Panels ── */
.detail-panel {
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.1);
    border-radius: var(--radius-lg);
    margin-bottom: 1rem;
    box-shadow: var(--shadow-card);
    overflow: hidden;
}
.detail-panel summary {
    padding: 1rem 1.5rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 1.05rem;
    list-style: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.detail-panel summary::-webkit-details-marker { display: none; }
.detail-panel summary::before {
    content: '\25B6';
    font-size: 0.7rem;
    transition: transform 0.15s;
    color: var(--text-secondary);
}
.detail-panel[open] summary::before { transform: rotate(90deg); }
.detail-panel .detail-body { padding: 0 1.5rem 1.25rem; }
.detail-panel .detail-desc {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 1rem;
}

.too-early-toggle {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    cursor: pointer;
}
.too-early-toggle input { cursor: pointer; }
.too-early-item { display: none; }
.show-too-early .too-early-item { display: flex; }

.strength-badge {
    display: inline-block;
    padding: 0.2rem 0.55rem;
    border-radius: var(--radius-sm);
    font-family: 'JetBrains Mono', monospace;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    white-space: nowrap;
    font-size: 0.7rem;
}

.practice-link {
    color: var(--cyan);
    text-decoration: none;
    font-size: 0.8rem;
    white-space: nowrap;
}
.practice-link:hover { text-decoration: underline; }

.section-heading {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--amethyst);
    margin-bottom: 0.75rem;
}

/* ── Analytics: Responsive ── */
@media (max-width: 720px) {
    .health-row { grid-template-columns: repeat(2, 1fr); }
    .module-grid { grid-template-columns: repeat(auto-fill, minmax(48px, 1fr)); }
}
@media (max-width: 480px) {
    .health-row { grid-template-columns: 1fr; }
    .module-grid { grid-template-columns: repeat(auto-fill, minmax(44px, 1fr)); }
}

/* ============================================================
   Dashboard Page Styles
   ============================================================ */
.dashboard-header {
    margin: var(--space-8) 0 var(--space-10);
}

.dashboard-header h1 {
    font-weight: 700;
    font-size: clamp(2rem, 5vw, 2.8rem);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--amethyst) 50%, var(--lavender) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Dashboard back link */
.dashboard-back-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    transition: color var(--transition-normal);
}

.dashboard-back-link:hover {
    color: var(--accent);
}

/* Dashboard action bar — Continue Learning + session timer in one row */
.dashboard-action-bar {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    margin-bottom: var(--space-4);
    padding: var(--space-4) var(--space-5);
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.12);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-card);
}
.resume-btn {
    display: inline-flex;
    align-items: center;
    padding: 0.6rem 1.4rem;
    background: var(--gradient-amethyst);
    color: #fff;
    font-weight: 700;
    font-size: 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    text-decoration: none;
    border-radius: var(--radius-full);
    transition: all var(--transition-normal);
    white-space: nowrap;
    box-shadow: 0 4px 16px rgba(167, 139, 250, 0.3);
}
.resume-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 24px rgba(167, 139, 250, 0.4);
    color: #fff;
}

/* Dashboard nav — feature pill row */
.dashboard-nav {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: var(--space-2);
    margin-bottom: var(--space-4);
}
.nav-pill--primary {
    background: var(--green-bright);
    color: var(--bg-base);
    border-color: var(--green-bright);
    font-weight: 700;
}
.nav-pill--primary:hover {
    background: var(--accent-hover);
    border-color: var(--accent-hover);
    color: var(--bg-base);
    box-shadow: var(--shadow-accent);
}

/* Segmented progress bar */
.progress-segments {
    display: flex;
    gap: 3px;
    height: 8px;
    margin-bottom: var(--space-4);
}
.progress-segment {
    flex: 1;
    border-radius: var(--radius-sm);
    background: var(--bg-muted);
    overflow: hidden;
    transition: background var(--transition-normal);
}
.progress-segment.complete {
    background: linear-gradient(90deg, var(--amethyst-dim), var(--amethyst));
    box-shadow: 0 0 8px rgba(167, 139, 250, 0.2);
}
.progress-segment.in-progress {
    background: linear-gradient(90deg, var(--forest) 50%, var(--bg-muted) 50%);
}

/* Session controls row — inside action bar */
.session-controls-row {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-left: auto;
}
.session-controls-row .session-duration {
    width: auto;
    padding: 0.45rem 0.7rem;
    border-radius: var(--radius-full);
    font-size: 0.8rem;
}
.session-controls-row .session-start-btn {
    padding: 0.45rem var(--space-4);
    border-radius: var(--radius-full);
    font-size: 0.8rem;
}
.session-controls-row .focus-toggle-slot {
    margin: 0;
    margin-left: auto;
}
.nav-pill {
    padding: 0.35rem 0.9rem;
    border: 1px solid rgba(167, 139, 250, 0.12);
    border-radius: var(--radius-full);
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-family: 'JetBrains Mono', monospace;
    transition: all var(--transition-normal);
    background: rgba(167, 139, 250, 0.04);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}
.nav-pill:hover {
    border-color: var(--amethyst);
    color: var(--amethyst);
    background: rgba(167, 139, 250, 0.08);
    box-shadow: 0 0 12px rgba(167, 139, 250, 0.1);
}

/* Stats Strip (compact pill badges) */
.stats-strip {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    margin-bottom: var(--space-3);
}
.stat-chip {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    background: rgba(167, 139, 250, 0.06);
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-full);
    padding: 0.4rem 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
    color: var(--text-secondary);
    box-shadow: var(--shadow-card);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}
.stat-chip::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 50% 0%, rgba(167, 139, 250, 0.08) 0%, transparent 70%);
    pointer-events: none;
}
.stat-chip-value {
    color: var(--amethyst);
    font-weight: 600;
}

/* Stats Detail (collapsible detailed stats) */
.stats-detail {
    margin-bottom: var(--space-6);
}
.stats-detail summary {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.35rem 0;
}
.stats-detail-content {
    background: rgba(196, 168, 232, 0.03);
    border: 1px solid rgba(196, 168, 232, 0.12);
    border-radius: 10px;
    padding: var(--space-4) var(--space-5);
    margin-top: var(--space-2);
    box-shadow: var(--shadow-sm);
}
.stats-row {
    display: flex;
    justify-content: space-around;
    padding: var(--space-3) 0;
    border-bottom: 1px solid var(--border-subtle);
}
.stats-row:last-of-type {
    border-bottom: none;
}
.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 0.15rem;
}
.stats-detail-content .stat-value {
    font-size: 1.5rem;
}
.stats-detail-content .stat-label {
    margin-top: 0.25rem;
}
.stats-detail-content #activity-heatmap {
    padding-top: var(--space-3);
    border-top: 1px solid var(--border-subtle);
    margin-top: 0.25rem;
    display: flex;
    justify-content: center;
}

/* Data management buttons */
.data-btn {
    padding: var(--space-2) var(--space-4);
    background: transparent;
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    transition: all var(--transition-normal);
}
.data-btn:hover {
    border-color: var(--orange);
    color: var(--orange);
}

@media (max-width: 720px) {
    .session-controls-row {
        flex-wrap: wrap;
    }
}
@media (max-width: 480px) {
    .stats-row {
        flex-wrap: wrap;
        gap: var(--space-2);
    }
    .stat-item {
        min-width: 70px;
    }
    .module-header h1 {
        font-size: 1.5rem;
    }
    .exercise {
        padding: var(--space-4);
        border-radius: var(--radius-md);
    }
    .exercise-header h3 {
        font-size: 0.95rem;
    }
    .session-stats {
        gap: var(--space-3);
    }
    .session-stat {
        padding: 0.6rem 0.75rem;
        min-width: 70px;
    }
    .session-stat-value {
        font-size: 1rem;
    }
    .flashcard,
    .flashcard-inner,
    .flashcard-front,
    .flashcard-back {
        min-height: 170px;
    }
    .flashcard-front,
    .flashcard-back {
        padding: var(--space-4);
    }
    .session-complete-stats {
        gap: var(--space-4);
    }
    h2 {
        font-size: 1.25rem;
    }
}
.session-start-btn {
    padding: 0.65rem var(--space-5);
    background: var(--green-bright);
    border: 1px solid var(--green-bright);
    border-radius: var(--radius-md);
    color: var(--bg-base);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    font-weight: 700;
    cursor: pointer;
    transition: all var(--transition-normal);
    white-space: nowrap;
}
.session-start-btn:hover {
    background: var(--accent-hover);
}
.session-duration {
    width: 100%;
    padding: 0.65rem 0.9rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-default);
    background: var(--bg-surface);
    color: var(--text);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
}

.session-timer {
    margin-bottom: var(--space-8);
}
.stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--orange);
    font-family: 'JetBrains Mono', monospace;
}
.stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: var(--space-2);
}
.module-list {
    margin-top: var(--space-2);
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-3);
}

@media (min-width: 768px) {
    .module-list {
        grid-template-columns: repeat(2, 1fr);
    }
}
.track-section {
    margin: var(--space-8) 0;
    grid-column: 1 / -1;
}
.track-title {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-secondary);
    margin-bottom: var(--space-4);
    font-weight: 600;
    padding-bottom: var(--space-2);
    border-bottom: none;
    display: inline-block;
    background: linear-gradient(90deg, var(--amethyst), transparent);
    background-size: 100% 2px;
    background-repeat: no-repeat;
    background-position: bottom;
}
.module-item {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    padding: var(--space-4) var(--space-5);
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.1);
    border-radius: var(--radius-lg);
    margin-bottom: 0;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-card);
    position: relative;
    overflow: hidden;
}
.module-item::before {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(167, 139, 250, 0.03) 0%, transparent 50%);
    opacity: 0;
    transition: opacity var(--transition-normal);
    pointer-events: none;
}
.module-item:hover {
    border-color: rgba(167, 139, 250, 0.25);
    box-shadow: var(--shadow-card-hover);
    transform: translateY(-2px);
}
.module-item:hover::before {
    opacity: 1;
}
.module-checkbox {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--green-bright);
}
.module-link {
    flex: 1;
    text-decoration: none;
    color: var(--text);
    display: flex;
    align-items: center;
    gap: var(--space-4);
}
.module-num {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    color: var(--text-secondary);
    min-width: 80px;
}
.module-name {
    font-weight: 500;
}
.module-item.completed {
    opacity: 1;
}
.module-item.completed .module-name {
    color: var(--text-secondary);
}
.module-item.completed::after {
    content: '\2713';
    position: absolute;
    top: var(--space-2);
    right: var(--space-3);
    width: 20px;
    height: 20px;
    background: var(--amethyst);
    color: var(--bg-base);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.65rem;
    font-weight: 700;
}
.last-studied {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-family: 'JetBrains Mono', monospace;
}
.clear-progress {
    padding: var(--space-2) var(--space-4);
    background: transparent;
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    transition: all var(--transition-normal);
}
.clear-progress:hover {
    border-color: var(--orange);
    color: var(--orange);
}
.export-notes {
    padding: var(--space-2) var(--space-4);
    background: transparent;
    border: 1px solid var(--purple);
    color: var(--purple);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    transition: all var(--transition-normal);
}
.export-notes:hover {
    background: var(--purple);
    color: var(--bg-base);
}
.data-management {
    margin-top: var(--space-8);
}
.data-actions {
    display: flex;
    gap: var(--space-4);
    flex-wrap: wrap;
}
.clear-progress--danger {
    border-color: var(--red);
    color: var(--red);
}

/* ============================================================
   Session Engine — shared practice session components
   ============================================================ */
[data-module="algorithms"] {
    --session-accent: var(--purple);
    --session-gradient: linear-gradient(90deg, var(--purple), var(--cyan));
}
[data-page="real-world-challenges"] {
    --session-accent: var(--red);
}
.session-stats {
    display: flex;
    gap: var(--space-6);
    margin: var(--space-6) 0;
    flex-wrap: wrap;
}
.session-stat {
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    padding: var(--space-4) var(--space-6);
    text-align: center;
    min-width: 100px;
}
.session-stat-value {
    font-size: 1.5rem;
    font-weight: 700;
    font-family: 'JetBrains Mono', monospace;
    color: var(--session-accent, var(--accent));
}
.session-stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}
.session-config {
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.12);
    border-radius: var(--radius-xl);
    padding: var(--space-8);
    margin: var(--space-6) 0;
    box-shadow: var(--shadow-card);
    position: relative;
    overflow: hidden;
}
.session-config::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 50% 0%, rgba(167, 139, 250, 0.06) 0%, transparent 60%);
    pointer-events: none;
}
.session-config-row {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    margin-bottom: var(--space-4);
    flex-wrap: wrap;
}
.session-config-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    min-width: 100px;
}
.session-config-options {
    display: flex;
    gap: var(--space-2);
    flex-wrap: wrap;
}
.session-option {
    background: transparent;
    border: 1px solid var(--border-default);
    color: var(--text);
    padding: 0.4rem 0.8rem;
    border-radius: var(--radius-full);
    font-size: 0.85rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    font-family: 'JetBrains Mono', monospace;
}
.session-option:hover {
    border-color: var(--session-accent, var(--accent));
    color: var(--session-accent, var(--accent));
}
.session-option.active {
    background: var(--session-accent, var(--accent));
    border-color: var(--session-accent, var(--accent));
    color: white;
    font-weight: 600;
    box-shadow: 0 0 12px rgba(167, 139, 250, 0.2);
}
.session-option:disabled {
    opacity: 0.35;
    cursor: not-allowed;
    pointer-events: none;
}
.session-start-area {
    margin-top: var(--space-4);
}
.session-start-btn-main {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-4) var(--space-8);
    background: var(--gradient-amethyst);
    color: #fff;
    border: none;
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-weight: 600;
    font-family: 'Space Grotesk', sans-serif;
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: 0 4px 16px rgba(167, 139, 250, 0.3);
}
.session-start-btn-main:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 24px rgba(167, 139, 250, 0.4);
}
.session-start-btn-main:active {
    transform: translateY(0);
    box-shadow: 0 2px 8px rgba(167, 139, 250, 0.2);
}
.session-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin: var(--space-6) 0 var(--space-4);
    flex-wrap: wrap;
    gap: var(--space-2);
}
.session-header-progress {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    color: var(--text-secondary);
}
.session-header-progress strong {
    color: var(--session-accent, var(--accent));
}
.session-category {
    font-size: 0.8rem;
    color: var(--cyan);
    font-family: 'JetBrains Mono', monospace;
}
.session-progress-bar {
    width: 100%;
    height: 4px;
    background: var(--bg-muted);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin: var(--space-4) 0;
}
.session-progress-fill {
    height: 100%;
    background: var(--session-gradient, linear-gradient(90deg, var(--green-bright), var(--orange)));
    border-radius: var(--radius-full);
    transition: width var(--transition-slow);
    box-shadow: 0 0 8px rgba(167, 139, 250, 0.3);
}
.session-nav-btns {
    display: flex;
    gap: var(--space-3);
    margin-top: var(--space-6);
}
.session-next-btn {
    padding: 0.6rem var(--space-6);
    background: var(--session-accent, var(--accent));
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 0.9rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all var(--transition-normal);
}
.session-next-btn:hover {
    filter: brightness(1.2);
    box-shadow: var(--shadow-glow-green);
}
.session-skip-btn {
    padding: 0.6rem var(--space-6);
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-default);
    border-radius: 6px;
    font-size: 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all var(--transition-normal);
}
.session-skip-btn:hover {
    border-color: var(--text);
    color: var(--text);
}
.session-complete {
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-xl);
    padding: var(--space-10);
    text-align: center;
    margin: var(--space-8) 0;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-card);
}
.session-complete::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 50% 0%, rgba(167, 139, 250, 0.1) 0%, transparent 60%);
    pointer-events: none;
}
.session-complete h2 {
    font-weight: 600;
    font-size: 1.8rem;
    background: linear-gradient(135deg, var(--amethyst), var(--lavender));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--space-4);
    animation: celebratePulse 2s ease-in-out;
}
@keyframes celebratePulse {
    0% { opacity: 0; transform: scale(0.95); }
    50% { opacity: 1; transform: scale(1.02); }
    100% { opacity: 1; transform: scale(1); }
}
.session-complete-stats {
    display: flex;
    gap: var(--space-8);
    justify-content: center;
    margin: var(--space-6) 0;
    flex-wrap: wrap;
}
.session-rating-guide {
    margin: var(--space-3) 0 var(--space-4);
    font-size: 0.8rem;
}
.session-rating-guide-toggle {
    color: var(--text-secondary);
    cursor: pointer;
    user-select: none;
    font-family: 'JetBrains Mono', monospace;
}
.session-rating-guide-toggle:hover {
    color: var(--text);
}
.session-rating-guide-arrow {
    display: inline-block;
    transition: transform var(--transition-normal);
    font-size: 0.7rem;
}
.session-rating-guide.open .session-rating-guide-arrow {
    transform: rotate(90deg);
}
.session-rating-guide-content {
    display: none;
    margin-top: var(--space-2);
    padding: var(--space-3) var(--space-4);
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: 6px;
    line-height: 1.6;
}
.session-rating-guide.open .session-rating-guide-content {
    display: block;
}
.session-rating-guide-content p {
    margin-bottom: 0.25rem;
}

/* ============================================================
   Daily Practice Plugin
   ============================================================ */
.dp-header {
    margin: var(--space-8) 0 var(--space-6);
}
.dp-empty {
    text-align: center;
    padding: var(--space-12);
    color: var(--text-secondary);
}
.dp-empty h3 {
    color: var(--text);
    margin-bottom: var(--space-2);
}

/* ============================================================
   Algorithm Practice Plugin
   ============================================================ */
.algo-header {
    margin: var(--space-8) 0 var(--space-6);
}
.algo-pattern-primer {
    border: 1px solid var(--border-default);
    border-left: 3px solid var(--lavender);
    border-radius: var(--radius-md);
    padding: var(--space-4);
    margin-bottom: var(--space-4);
    background: rgba(196, 168, 232, 0.04);
}
.algo-pattern-primer summary {
    color: var(--purple);
    font-weight: 600;
    cursor: pointer;
}
.algo-help-section {
    margin-top: var(--space-12);
    padding-top: var(--space-8);
    border-top: 1px solid var(--border-subtle);
}
.algo-help-section summary {
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 0.9rem;
}
.algo-help-content {
    margin-top: var(--space-4);
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.8;
}
.algo-help-content h4 {
    color: var(--text);
    margin: var(--space-4) 0 var(--space-2);
}
.algo-help-content code {
    background: var(--bg-muted);
    padding: 0.1rem 0.3rem;
    border-radius: 3px;
    font-size: 0.8rem;
}

/* Category Grid */
.algo-category-section {
    margin-bottom: var(--space-4);
}
.algo-category-section .session-config-label {
    display: block;
    margin-bottom: var(--space-2);
}
.algo-category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: var(--space-3);
    margin-bottom: var(--space-4);
}
.algo-cat-card {
    background: var(--bg-surface);
    border: 1px solid rgba(167, 139, 250, 0.1);
    border-radius: var(--radius-lg);
    padding: var(--space-4);
    cursor: pointer;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-card);
}
.algo-cat-card:hover {
    border-color: rgba(196, 168, 232, 0.3);
    transform: translateY(-2px);
    box-shadow: var(--shadow-card-hover);
    background: rgba(167, 139, 250, 0.04);
}
.algo-cat-card.active {
    border-color: var(--purple);
    box-shadow: 0 0 0 1px var(--purple), var(--shadow-card);
    background: rgba(167, 139, 250, 0.06);
}
.algo-cat-icon {
    font-size: 1.5rem;
    margin-bottom: 0.25rem;
}
.algo-cat-name {
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: var(--space-2);
}
.algo-cat-mastery-bar {
    width: 100%;
    height: 4px;
    background: var(--bg-muted);
    border-radius: var(--radius-full);
    overflow: hidden;
    margin-bottom: var(--space-2);
}
.mastery-fill {
    height: 100%;
    background: var(--session-gradient, linear-gradient(90deg, var(--amethyst-dim), var(--amethyst)));
    border-radius: var(--radius-full);
    transition: width var(--transition-slow);
    box-shadow: 0 0 6px rgba(167, 139, 250, 0.2);
}
.algo-cat-tiers {
    display: flex;
    gap: 0.35rem;
    flex-wrap: wrap;
}
.algo-cat-tiers .tier {
    font-size: 0.7rem;
    padding: 0.1rem 0.35rem;
    border-radius: 3px;
    background: var(--bg-muted);
    color: var(--text-secondary);
}
.algo-cat-tiers .tier.unlocked {
    color: var(--green-bright);
}
.algo-cat-tiers .tier.locked {
    opacity: 0.5;
    color: var(--text-secondary);
}

/* Blind Mode */
.algo-blind-hint {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-left: 0.25rem;
}

/* Assessment Mode */
.assessment-exercise {
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    padding: var(--space-6);
}
.assessment-exercise h4 {
    margin-top: 0;
    margin-bottom: var(--space-3);
}
.assessment-exercise .exercise-desc {
    margin-bottom: var(--space-4);
    line-height: 1.6;
}
.assessment-actions {
    margin-top: var(--space-6);
    text-align: center;
}
.assessment-grade-btn {
    background: var(--purple);
    color: var(--bg-base);
    border: none;
    padding: var(--space-3) var(--space-8);
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: opacity var(--transition-normal);
}
.assessment-grade-btn:hover {
    opacity: 0.85;
}
.assessment-reveal {
    margin-top: var(--space-6);
}
.assessment-reveal .self-rating {
    text-align: center;
    padding: var(--space-4);
    background: var(--bg-muted);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-4);
}
.assessment-reveal .self-rating-label {
    display: block;
    margin-bottom: var(--space-3);
    font-weight: 600;
}
.assessment-reveal .self-rating-buttons {
    display: flex;
    gap: var(--space-2);
    justify-content: center;
    flex-wrap: wrap;
}
.assessment-reveal .rating-btn {
    padding: var(--space-2) var(--space-5);
    border: 1px solid var(--border-default);
    border-radius: 6px;
    background: var(--bg-surface);
    color: var(--text);
    cursor: pointer;
    font-size: 0.9rem;
    transition: border-color var(--transition-normal);
}
.assessment-reveal .rating-btn:hover:not(:disabled) {
    border-color: var(--purple);
}
.assessment-reveal .rating-btn:disabled {
    opacity: 0.5;
    cursor: default;
}
.assessment-reveal .rating-btn.selected {
    border-color: var(--purple);
    background: var(--purple);
    color: var(--bg-base);
    opacity: 1;
}
.assessment-solution-reveal {
    animation: fadeInReveal 0.4s ease;
}
@keyframes fadeInReveal {
    from { opacity: 0; transform: translateY(4px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Pattern Drill */
.pattern-drill-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    padding: var(--space-6);
}
.pattern-drill-card h4 {
    margin-top: 0;
    color: var(--purple);
}
.pattern-drill-desc {
    line-height: 1.6;
    margin-bottom: var(--space-4);
}
.pattern-drill-choices {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-3);
    margin-top: var(--space-6);
}
.pattern-choice {
    padding: var(--space-3) var(--space-4);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    background: var(--bg-surface);
    color: var(--text);
    cursor: pointer;
    font-size: 0.9rem;
    text-align: left;
    transition: border-color var(--transition-normal), background var(--transition-normal);
}
.pattern-choice:hover:not(:disabled) {
    border-color: var(--purple);
}
.pattern-choice:disabled {
    cursor: default;
}
.pattern-choice.correct {
    border-color: var(--green-bright);
    background: rgba(167, 139, 250, 0.1);
    color: var(--green-bright);
    box-shadow: var(--shadow-glow-green);
}
.pattern-choice.incorrect {
    border-color: var(--red);
    background: rgba(224, 96, 112, 0.06);
    color: var(--red);
}
.pattern-drill-result {
    margin-top: var(--space-6);
    animation: fadeInReveal 0.4s ease;
}
.pattern-result-icon {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: var(--space-3);
}
.pattern-drill-result .pattern-result-icon:first-child {
    color: var(--green-bright);
}
.pattern-drill-result:has(.incorrect) .pattern-result-icon:first-child,
.pattern-drill-card:has(.pattern-choice.incorrect) .pattern-result-icon {
    color: var(--red);
}
.pattern-primer {
    background: var(--bg-muted);
    border-radius: 6px;
    padding: var(--space-4);
    font-size: 0.9rem;
    line-height: 1.6;
}
.pattern-primer strong {
    color: var(--purple);
}
.pattern-primer p {
    margin: 0.25rem 0;
}
.pattern-drill-results h3 {
    margin-top: 0;
    color: var(--purple);
}

/* Drill info box */
.algo-drill-info {
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: 6px;
    padding: var(--space-4);
    margin-bottom: var(--space-2);
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

@media (max-width: 600px) {
    .algo-category-grid {
        grid-template-columns: 1fr 1fr;
    }
    .pattern-drill-choices {
        grid-template-columns: 1fr;
    }
}
@media (max-width: 400px) {
    .algo-category-grid {
        grid-template-columns: 1fr;
    }
}

/* ============================================================
   Inline Exercises (interleaved with lesson content)
   ============================================================ */
.inline-exercises {
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-radius: var(--radius-2xl);
    background: rgba(167, 139, 250, 0.05);
    padding: var(--space-6);
    margin: var(--space-8) 0;
    box-shadow: var(--shadow-card);
    position: relative;
    overflow: hidden;
}

.inline-exercises::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--amethyst), var(--lavender), transparent);
}

.inline-exercises-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-4);
}

.inline-exercises-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--amethyst);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.inline-exercises-label::before {
    content: '';
    display: inline-block;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--amethyst);
    animation: tagPulse 2s ease-in-out infinite;
}

.review-all-warmups {
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: var(--space-2) var(--space-4);
    margin: var(--space-8) 0;
}

.review-all-warmups > summary {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    color: var(--text-secondary);
    padding: var(--space-2) 0;
}

.review-all-warmups > summary:hover {
    color: var(--green-bright);
}

/* --- Split layout for inline exercises (wide screens) --- */

.inline-exercises-body.split-layout {
    display: grid;
    grid-template-columns: 1fr minmax(340px, 35%);
    gap: var(--space-8);
    align-items: start;
}

.inline-exercises-ref {
    position: sticky;
    top: var(--space-4);
    max-height: calc(100vh - 2rem);
    overflow-y: auto;
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    padding: var(--space-4);
    box-shadow: var(--shadow-sm);
}

.inline-exercises-ref-title {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--cyan);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: var(--space-3);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.inline-exercises-ref-hide {
    background: none;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.65rem;
    padding: 0.15rem 0.4rem;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    transition: color var(--transition-normal), border-color var(--transition-normal);
}

.inline-exercises-ref-hide:hover {
    color: var(--cyan);
    border-color: var(--cyan);
}

.inline-exercises-ref-show {
    background: none;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    padding: 0.25rem 0.6rem;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    transition: color var(--transition-normal), border-color var(--transition-normal);
    margin-bottom: var(--space-3);
}

.inline-exercises-ref-show:hover {
    color: var(--cyan);
    border-color: var(--cyan);
}

.inline-exercises-ref h3,
.inline-exercises-ref h4 {
    font-size: 0.8rem;
    color: var(--cyan);
    margin: var(--space-3) 0 0.25rem;
}

.inline-exercises-ref h3:first-child,
.inline-exercises-ref h4:first-child {
    margin-top: 0;
}

.inline-exercises-ref pre {
    font-size: 0.78rem !important;
    line-height: 1.5 !important;
    padding: 0.5rem 0.75rem !important;
    margin: 0.25rem 0 0.5rem !important;
    border-radius: 6px;
}

.inline-exercises-ref .code-labeled,
.inline-exercises-ref .code-compare {
    margin: 0.25rem 0 0.5rem;
}

.inline-exercises-ref .code-label {
    font-size: 0.7rem;
}

/* Collapsible reference for narrow screens */
.inline-exercises-ref-details {
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-4);
    background: var(--bg-surface);
}

.inline-exercises-ref-details > summary {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--cyan);
    padding: var(--space-3) var(--space-4);
    cursor: pointer;
}

.inline-exercises-ref-details > summary:hover {
    color: var(--green-bright);
}

.inline-exercises-ref-details > .inline-exercises-ref {
    position: static;
    max-height: 50vh;
    border: none;
    border-top: 1px solid var(--border-default);
    border-radius: 0 0 var(--radius-md) var(--radius-md);
}

@media print {
    .inline-exercises-body.split-layout {
        display: block;
    }
    .inline-exercises-ref {
        position: static;
        max-height: none;
        overflow: visible;
        margin-top: var(--space-4);
    }
}

/* ============================================================
   Real-World Challenges Plugin
   ============================================================ */
.rwc-challenge-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-4);
}
.rwc-card {
    background: var(--bg-surface);
    border: 1px solid rgba(224, 96, 112, 0.1);
    border-radius: var(--radius-lg);
    padding: var(--space-6);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-card);
}
.rwc-card:hover {
    border-color: rgba(224, 96, 112, 0.25);
    box-shadow: var(--shadow-card-hover), 0 0 20px rgba(224, 96, 112, 0.06);
    transform: translateY(-1px);
}
.rwc-card-header {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    margin-bottom: var(--space-3);
    flex-wrap: wrap;
}
.rwc-card-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text);
    flex: 1;
    min-width: 200px;
}
.rwc-difficulty {
    display: inline-flex;
    gap: 2px;
}
.rwc-difficulty-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--bg-muted);
}
.rwc-difficulty-dot.filled {
    background: linear-gradient(135deg, var(--coral), #E88090);
    box-shadow: 0 0 6px rgba(224, 96, 112, 0.3);
}
.rwc-status-badge {
    padding: 0.2rem 0.6rem;
    border-radius: var(--radius-full);
    font-size: 0.7rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', monospace;
}
.rwc-status-badge.not-started {
    background: var(--bg-muted);
    color: var(--text-secondary);
}
.rwc-status-badge.in-progress {
    background: rgba(224, 151, 106, 0.12);
    color: var(--orange);
}
.rwc-status-badge.completed {
    background: rgba(167, 139, 250, 0.12);
    color: var(--green-bright);
}
.rwc-tags {
    display: flex;
    gap: var(--space-2);
    flex-wrap: wrap;
    margin-bottom: var(--space-3);
}
.rwc-company-tag {
    padding: 0.2rem 0.6rem;
    border-radius: var(--radius-full);
    font-size: 0.7rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', monospace;
    background: rgba(224, 96, 112, 0.06);
    color: var(--red);
    border: 1px solid rgba(224, 96, 112, 0.15);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}
.rwc-concept-tag {
    padding: 0.2rem 0.6rem;
    border-radius: var(--radius-full);
    font-size: 0.7rem;
    font-family: 'JetBrains Mono', monospace;
    background: rgba(124, 180, 224, 0.06);
    color: var(--cyan);
    border: 1px solid rgba(124, 180, 224, 0.15);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}
.rwc-source {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-style: italic;
    margin-bottom: var(--space-3);
}
.rwc-source-label {
    font-style: normal;
    font-weight: 600;
    color: var(--text);
}
.rwc-source a {
    color: var(--cyan);
    text-decoration: none;
}
.rwc-source a:hover {
    text-decoration: underline;
}
.rwc-details {
    margin-top: var(--space-3);
}
.rwc-details summary {
    cursor: pointer;
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-family: 'JetBrains Mono', monospace;
    padding: var(--space-2) 0;
    user-select: none;
}
.rwc-details summary:hover {
    color: var(--text);
}
.rwc-details[open] summary {
    color: var(--text);
    margin-bottom: var(--space-3);
}
.rwc-section {
    margin-bottom: var(--space-5);
}
.rwc-section-title {
    font-size: 0.85rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: var(--space-2);
    font-family: 'Space Grotesk', sans-serif;
}
.rwc-requirements {
    font-size: 0.9rem;
    line-height: 1.7;
    color: var(--text);
}
.rwc-requirements code {
    background: var(--bg-muted);
    padding: 0.15rem 0.4rem;
    border-radius: 3px;
    font-size: 0.85em;
}
.rwc-requirements pre {
    background: var(--bg-base);
    padding: var(--space-4);
    border-radius: 6px;
    overflow-x: auto;
    margin: var(--space-3) 0;
}
.rwc-requirements pre code {
    background: none;
    padding: 0;
}
.rwc-requirements ul, .rwc-requirements ol {
    padding-left: var(--space-6);
    margin: var(--space-2) 0;
}
.rwc-checklist {
    list-style: none;
    padding-left: 0;
}
.rwc-checklist li {
    padding: 0.25rem 0;
    font-size: 0.9rem;
    color: var(--text);
}
.rwc-check-label {
    display: flex;
    align-items: flex-start;
    gap: var(--space-2);
    cursor: pointer;
}
.rwc-check-label span {
    flex: 1;
}
.rwc-check {
    margin-top: 0.3rem;
    accent-color: var(--green-bright);
    cursor: pointer;
}
.rwc-check:checked + span {
    text-decoration: line-through;
    color: var(--text-secondary);
}
.rwc-hints-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}
.rwc-hint-toggle {
    margin: 0;
}
.rwc-hint-toggle summary {
    cursor: pointer;
    color: var(--orange);
    font-size: 0.85rem;
    font-family: 'JetBrains Mono', monospace;
    padding: 0.35rem 0;
    user-select: none;
}
.rwc-hint-toggle summary:hover {
    color: var(--text);
}
.rwc-hint-content {
    padding: var(--space-2) 0 var(--space-2) var(--space-4);
    border-left: 2px solid var(--orange);
    font-size: 0.9rem;
    line-height: 1.6;
    color: var(--text);
}
.rwc-hint-content code {
    background: var(--bg-muted);
    padding: 0.15rem 0.4rem;
    border-radius: 3px;
    font-size: 0.85em;
}
.rwc-extensions {
    list-style: none;
    padding-left: 0;
}
.rwc-extensions li {
    padding: 0.35rem 0;
    padding-left: var(--space-6);
    position: relative;
    font-size: 0.9rem;
    color: var(--text-secondary);
}
.rwc-extensions li::before {
    content: '+';
    position: absolute;
    left: 0;
    color: var(--green-bright);
    font-weight: 700;
}
.rwc-action-btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-4);
    border-radius: 6px;
    font-size: 0.85rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all var(--transition-normal);
    border: 1px solid;
    margin-top: var(--space-3);
}
.rwc-action-btn.start {
    background: transparent;
    color: var(--orange);
    border-color: var(--orange);
}
.rwc-action-btn.start:hover {
    background: var(--orange);
    color: #fff;
    box-shadow: var(--shadow-glow-orange);
}
.rwc-action-btn.complete {
    background: transparent;
    color: var(--green-bright);
    border-color: var(--green-bright);
}
.rwc-action-btn.complete:hover {
    background: var(--green-bright);
    color: var(--bg-base);
    box-shadow: var(--shadow-glow-green);
}
.rwc-action-btn.reopen {
    background: transparent;
    color: var(--text-secondary);
    border-color: var(--border-default);
}
.rwc-action-btn.reopen:hover {
    border-color: var(--text-secondary);
    color: var(--text);
}
.rwc-action-btn.reset {
    background: transparent;
    color: var(--text-secondary);
    border-color: var(--border-default);
    font-size: 0.75rem;
    padding: 0.35rem 0.75rem;
}
.rwc-action-btn.reset:hover {
    border-color: var(--text-secondary);
    color: var(--text);
}
.rwc-action-group {
    display: flex;
    gap: var(--space-2);
    align-items: center;
    margin-top: var(--space-3);
}
.rwc-action-group .rwc-action-btn {
    margin-top: 0;
}
.rwc-empty {
    text-align: center;
    padding: var(--space-12);
    color: var(--text-secondary);
}
@media (max-width: 600px) {
    .rwc-card-header {
        flex-direction: column;
        align-items: flex-start;
    }
}

/* ============================================
   Module Page: Exercise section divider
   ============================================ */
#warmups-container::before {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--accent);
    border-radius: var(--radius-full);
    margin: var(--space-12) 0 var(--space-8);
    opacity: 0.5;
}

/* ============================================
   Personal notes textarea
   ============================================ */
.personal-notes-textarea {
    width: 100%;
    min-height: 100px;
    margin-top: var(--space-2);
    padding: var(--space-3);
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-sm);
    color: var(--text);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    resize: vertical;
    transition: border-color var(--transition-normal), background var(--transition-normal);
}

.personal-notes-textarea:focus {
    outline: none;
    border-color: var(--purple);
    background: var(--bg-surface);
    box-shadow: 0 0 0 2px var(--purple-glow);
}

/* ============================================
   Reduced Motion
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    .scroll-progress {
        transition: none;
    }
    .quick-btn:hover,
    .course-card:hover,
    .module-item:hover,
    .algo-cat-card:hover,
    .rwc-card:hover,
    .exercise:hover,
    .nav-btn:hover,
    .stat-card:hover,
    .resume-btn:hover,
    .session-start-btn-main:hover,
    .flashcard:hover .flashcard-front,
    .flashcard:hover .flashcard-back,
    .lesson pre:hover {
        transform: none;
    }
    .module-item,
    .course-card,
    .dashboard-header,
    .stats-strip,
    .progress-segments,
    .dashboard-action-bar,
    .dashboard-nav {
        animation: none !important;
        opacity: 1 !important;
    }
    .module-tag::before,
    .inline-exercises-label::before {
        animation: none !important;
    }
}

/* ============================================================
   Staggered Fade-In Animations
   ============================================================ */
@keyframes fadeUp {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Dashboard staggered entry animations */
.dashboard-header {
    animation: fadeUp 0.4s ease forwards;
}
.stats-strip {
    opacity: 0;
    animation: fadeUp 0.4s ease 0.05s forwards;
}
.progress-segments {
    opacity: 0;
    animation: fadeUp 0.4s ease 0.1s forwards;
}
.dashboard-action-bar {
    opacity: 0;
    animation: fadeUp 0.4s ease 0.15s forwards;
}
.dashboard-nav {
    opacity: 0;
    animation: fadeUp 0.4s ease 0.2s forwards;
}

.module-item {
    opacity: 0;
    animation: fadeUp 0.4s ease forwards;
}
.module-item:nth-child(1) { animation-delay: 0.03s; }
.module-item:nth-child(2) { animation-delay: 0.06s; }
.module-item:nth-child(3) { animation-delay: 0.09s; }
.module-item:nth-child(4) { animation-delay: 0.12s; }
.module-item:nth-child(5) { animation-delay: 0.15s; }
.module-item:nth-child(6) { animation-delay: 0.18s; }
.module-item:nth-child(7) { animation-delay: 0.21s; }
.module-item:nth-child(8) { animation-delay: 0.24s; }
.module-item:nth-child(9) { animation-delay: 0.27s; }
.module-item:nth-child(10) { animation-delay: 0.3s; }
.module-item:nth-child(11) { animation-delay: 0.33s; }
.module-item:nth-child(12) { animation-delay: 0.36s; }
.module-item:nth-child(13) { animation-delay: 0.39s; }
.module-item:nth-child(14) { animation-delay: 0.42s; }
.module-item:nth-child(15) { animation-delay: 0.45s; }
.module-item:nth-child(n+16) { animation-delay: 0.48s; }

.course-card:hover {
    transform: translateY(-1px);
}

/* ============================================================
   Completion Celebration
   ============================================================ */
@keyframes celebrate {
    0% { box-shadow: var(--shadow-card), 0 0 0 0 rgba(140, 198, 140, 0.3); }
    30% { box-shadow: var(--shadow-card), 0 0 16px 4px rgba(140, 198, 140, 0.2); }
    60% { box-shadow: var(--shadow-card), 0 0 20px 6px rgba(167, 139, 250, 0.15); }
    100% { box-shadow: var(--shadow-card), 0 0 0 0 rgba(167, 139, 250, 0); }
}
.exercise.just-completed {
    animation: celebrate 0.8s ease;
}

/* ============================================
   Scaffold Drill System
   ============================================ */

.drill-btn {
    background: transparent;
    border: 2px solid var(--accent);
    color: var(--accent);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    margin-top: 0.75rem;
    transition: all 0.2s;
    font-size: 0.85rem;
    display: inline-block;
}
.drill-btn:hover {
    background: var(--accent);
    color: var(--bg-base);
    transform: translateY(-1px);
    box-shadow: var(--shadow-glow-green);
}

.drill-container {
    border: 1px solid rgba(167, 139, 250, 0.15);
    border-left: none;
    border-radius: var(--radius-lg);
    padding: 1.25rem;
    padding-left: calc(1.25rem + 4px);
    margin-top: 1rem;
    background: rgba(167, 139, 250, 0.04);
    animation: fadeInReveal 0.3s ease;
    position: relative;
    box-shadow: var(--shadow-card);
}
.drill-container::after {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 4px;
    background: linear-gradient(180deg, var(--amethyst), var(--lavender));
    border-radius: 4px 0 0 4px;
}
.drill-container-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid rgba(167, 139, 250, 0.12);
}
.drill-container-title {
    font-weight: 600;
    color: var(--amethyst);
    font-size: 0.95rem;
}
.drill-container-subtitle {
    font-size: 0.8rem;
    color: var(--text-secondary);
}
.drill-close-btn {
    margin-left: auto;
    background: transparent;
    border: 1px solid var(--text-secondary);
    color: var(--text-secondary);
    padding: 0.2rem 0.6rem;
    border-radius: 4px;
    font-size: 0.75rem;
    cursor: pointer;
}
.drill-close-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* Step indicator */
.drill-step-indicator {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}
.drill-step-count {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Cognitive type labels */
.drill-type-label {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.15rem 0.5rem;
    border-radius: 4px;
}
.drill-type-trace    { background: var(--slate);    color: var(--bg-base); }
.drill-type-fix      { background: var(--amber);    color: white; }
.drill-type-complete { background: var(--lavender);  color: white; }
.drill-type-produce  { background: var(--sage);     color: var(--bg-base); }

/* Exercise cards inside drill — strip outer chrome */
.drill-step-content .exercise {
    border: none;
    padding: 0;
    margin: 0;
    background: transparent;
    box-shadow: none;
}
.drill-step-content .exercise::before {
    display: none;
}
.drill-step-content .exercise:hover {
    box-shadow: none;
    transform: none;
}
.drill-step-content .exercise h4 {
    font-size: 0.9rem;
    margin-bottom: 0.4rem;
}

/* Next step / finish button */
.drill-next-btn {
    display: block;
    width: 100%;
    margin-top: 1rem;
    padding: 0.6rem 1rem;
    background: transparent;
    border: 1px solid var(--accent);
    color: var(--accent);
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.85rem;
    cursor: pointer;
    transition: all 0.2s;
}
.drill-next-btn:hover {
    background: var(--accent);
    color: var(--bg-base);
}

/* Completion state */
.drill-complete {
    text-align: center;
    padding: 1.5rem;
    color: var(--sage);
    font-weight: 600;
}
.drill-complete-sub {
    color: var(--text-secondary);
    font-weight: 400;
    font-size: 0.85rem;
    margin-top: 0.25rem;
}

/* ── Concept Mastery Panel ── */

.concept-mastery-panel {
    background: rgba(167, 139, 250, 0.03);
    border: 1px solid rgba(167, 139, 250, 0.12);
    border-radius: 10px;
    padding: 1.25rem;
    margin-bottom: 1.5rem;
}
.concept-mastery-title {
    font-weight: 600;
    font-size: 1rem;
    margin-bottom: 1rem;
    color: var(--text);
}
.concept-mastery-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border-subtle);
}
.concept-mastery-item:last-child { border-bottom: none; }
.concept-mastery-name {
    flex: 1;
    font-size: 0.85rem;
    color: var(--text);
    min-width: 0;
}
.concept-mastery-bar-container {
    width: 80px;
    height: 6px;
    background: var(--border-default);
    border-radius: 3px;
    overflow: hidden;
    flex-shrink: 0;
}
.concept-mastery-bar {
    height: 100%;
    border-radius: 3px;
    transition: width 0.3s;
}
.concept-mastery-badge {
    font-size: 0.7rem;
    font-weight: 600;
    padding: 0.1rem 0.4rem;
    border-radius: 4px;
    white-space: nowrap;
    flex-shrink: 0;
}
.concept-mastery-practice-btn {
    background: transparent;
    border: 1px solid var(--accent);
    color: var(--accent);
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-size: 0.7rem;
    cursor: pointer;
    transition: all 0.2s;
    flex-shrink: 0;
}
.concept-mastery-practice-btn:hover {
    background: var(--accent);
    color: var(--bg-base);
}