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

/* ============================================
   1. CSS Variables
   ============================================ */
:root {
    /* Dark mode (default) */
    --bg-dark: #0a0a0f;
    --bg-card: #12121a;
    --bg-code: #1a1a24;
    --bg-lighter: #1f1f2a;
    --green-bright: #00ff9d;
    --green-dim: #00cc7d;
    --green-glow: rgba(0, 255, 157, 0.15);
    --orange: #ff9d00;
    --purple: #9d00ff;
    --blue: #00b4ff;
    --cyan: #00d4ff;
    --red: #ff4757;
    --text-main: #e0e0e0;
    --text: var(--text-main);
    --text-dim: #888;
    --border: #2a2a3a;
}

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

/* ============================================
   2. Reset and Base Styles
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Space Grotesk', sans-serif;
    background: var(--bg-dark);
    color: var(--text-main);
    line-height: 1.7;
    min-height: 100vh;
}

/* ============================================
   3. Container/Layout
   ============================================ */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem;
    transition: margin-left 0.3s ease;
}

/* ============================================
   5. Navigation (Top Nav Links)
   ============================================ */
nav.top-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 2rem;
}

nav.top-nav a {
    color: var(--text-dim);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s;
}

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

/* ============================================
   6. Module Header Styles
   ============================================ */
.module-header {
    margin-bottom: 3rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border);
}

.module-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--green-bright);
    margin-bottom: 0.5rem;
}

.module-tag {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    color: var(--green-bright);
    margin-bottom: 0.5rem;
}

.module-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

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

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

/* ============================================
   8. Code Blocks with Syntax Highlighting
   ============================================ */
.code-block {
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1.5rem;
    margin: 1.5rem 0;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
}

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

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

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

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

/* Markdown-generated code blocks (pre > code) */
.lesson pre {
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1.5rem;
    margin: 1.5rem 0;
    overflow-x: auto;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    line-height: 1.6;
}

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

/* Code comparison layout (side-by-side labeled blocks) */
.code-compare {
    display: grid;
    grid-template-columns: 1fr 1fr;
    margin: 1.5rem 0;
    border: 1px solid var(--border);
    border-radius: 8px;
    overflow: hidden;
}

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

.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 var(--border);
    border-radius: 8px;
    overflow: hidden;
    margin: 1.5rem 0;
}

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

/* Language label header */
.code-header {
    background: var(--bg-lighter);
    padding: 0.4rem 1rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-dim);
    border-bottom: 1px solid var(--border);
}

/* Syntax highlighting (highlight.js classes using theme variables) */
.hljs { color: var(--text-main); }
.hljs-keyword,
.hljs-selector-tag,
.hljs-built_in,
.hljs-name { color: var(--purple, #9d00ff); }
.hljs-string,
.hljs-attr,
.hljs-symbol,
.hljs-bullet,
.hljs-addition { color: var(--green-bright, #00ff9d); }
.hljs-title,
.hljs-title.function_,
.hljs-section { color: var(--blue, #00b4ff); }
.hljs-comment,
.hljs-quote,
.hljs-deletion { color: var(--text-dim, #888); font-style: italic; }
.hljs-type,
.hljs-template-tag,
.hljs-class .hljs-title { color: var(--cyan, #00d4ff); }
.hljs-number,
.hljs-literal,
.hljs-variable,
.hljs-template-variable,
.hljs-tag .hljs-attr { color: var(--orange, #ff9d00); }
.hljs-meta,
.hljs-doctag { color: var(--text-dim); }
.hljs-params { color: var(--text-main); }
.hljs-punctuation { color: var(--text-dim); }

@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);
    }
}

/* Exercise jump-to box */
.exercise-jump-box {
    background: var(--bg-card);
    border-radius: 8px;
    padding: 1rem 1.5rem;
    margin: 1rem 0 2rem 0;
}

.exercise-jump-label {
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text);
}

.exercise-jump-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem 1rem;
    font-size: 0.9rem;
}

.exercise-jump-links a {
    text-decoration: none;
    transition: opacity 0.2s;
}

.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: 1.25rem;
    border-radius: 8px;
    margin: 1.5rem 0;
    border-left: 4px solid;
}

.tip {
    background: rgba(0, 255, 157, 0.1);
    border-left-color: var(--green-bright);
}

.tip::before {
    content: '💡 Tip';
    display: block;
    font-weight: 600;
    color: var(--green-bright);
    margin-bottom: 0.5rem;
}

.warning {
    background: rgba(255, 71, 87, 0.1);
    border-left-color: var(--red);
}

.warning::before {
    content: '⚠️ Warning';
    display: block;
    font-weight: 600;
    color: var(--red);
    margin-bottom: 0.5rem;
}

.info {
    background: rgba(0, 180, 255, 0.1);
    border-left-color: var(--blue);
}

.info::before {
    content: 'ℹ️ Note';
    display: block;
    font-weight: 600;
    color: var(--blue);
    margin-bottom: 0.5rem;
}

/* ============================================
   11. Exercises and Hints/Solutions
   ============================================ */
.js-required {
    color: var(--text-dim);
    font-style: italic;
    padding: 1rem;
    text-align: center;
}

.exercise {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2rem;
    margin: 2rem 0;
}

.exercise-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

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

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

.exercise p {
    margin-bottom: 1rem;
}

.hint, .solution {
    margin-top: 1rem;
}

.hint-toggle, .solution-toggle {
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 0.75rem 1rem;
    color: var(--text-main);
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s;
    width: 100%;
    text-align: left;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

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

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

/* Details/Summary collapsible elements */
details {
    margin: 0.75rem 0;
}

details summary {
    cursor: pointer;
    color: var(--cyan);
    font-weight: 500;
    padding: 0.5rem 0;
    user-select: none;
    list-style: none;
}

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

details summary::before {
    content: "▶ ";
    font-size: 0.8em;
    margin-right: 0.25rem;
}

details[open] summary::before {
    content: "▼ ";
}

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

details[open] summary {
    margin-bottom: 0.5rem;
}

details .hint-content {
    display: block;
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-left: 3px solid var(--orange);
    border-radius: 4px;
    padding: 1rem;
    margin-top: 0.5rem;
}

/* ============================================
   12. Navigation Buttons
   ============================================ */
.nav-buttons {
    display: flex;
    justify-content: space-between;
    margin-top: 4rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
}

.nav-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-main);
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.3s;
}

.nav-btn:hover {
    border-color: var(--green-bright);
    box-shadow: 0 4px 20px var(--green-glow);
}

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

.nav-btn.primary:hover {
    background: #fff;
}

/* ============================================
   13. Lists and Inline Code
   ============================================ */
ul, ol {
    margin: 1rem 0 1rem 2rem;
}

li {
    margin-bottom: 0.5rem;
}

code:not(.code-block code):not(pre code) {
    background: var(--bg-code);
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
    color: var(--green-bright);
}

h2, h3, h4 {
    margin-top: 2rem;
    margin-bottom: 1rem;
}

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

h3 {
    font-size: 1.25rem;
}

p {
    margin-bottom: 1rem;
}

a {
    color: var(--green-bright);
    text-decoration: none;
    transition: opacity 0.2s;
}

a:hover {
    opacity: 0.8;
}

/* ============================================
   14. Theme Toggle Button
   ============================================ */
.theme-toggle {
    position: fixed;
    top: 1rem;
    right: 1rem;
    width: 44px;
    height: 44px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    z-index: 101;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: var(--text-main);
    transition: all 0.3s;
}

.theme-picker {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 101;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 0.35rem;
}

.theme-picker-label {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.theme-select {
    background: var(--bg-card);
    color: var(--text-main);
    border: 1px solid var(--border);
    border-radius: 999px;
    padding: 0.5rem 1rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.25);
    cursor: pointer;
    min-width: 180px;
}

.theme-select:focus {
    outline: 2px solid var(--green-bright);
    outline-offset: 2px;
}

.theme-actions {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.focus-toggle {
    border: 1px solid var(--border);
    background: var(--bg-card);
    color: var(--text-dim);
    border-radius: 999px;
    padding: 0.35rem 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all 0.2s;
    min-width: 180px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.show-timer-toggle {
    border: 1px solid var(--border);
    background: var(--bg-card);
    color: var(--text-dim);
    border-radius: 999px;
    padding: 0.35rem 0.9rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all 0.2s;
    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: 0.75rem 0 2rem;
    display: flex;
    justify-content: flex-start;
}

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

.focus-toggle.active {
    background: var(--green-bright);
    color: var(--bg-dark);
    border-color: var(--green-bright);
}

/* ============================================
   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 0.2s ease;
}

body.focus-mode .lesson {
    opacity: 1;
}

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

body.focus-mode .theme-picker-label,
body.focus-mode .theme-select {
    display: none !important;
}

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

.theme-toggle:hover {
    border-color: var(--green-bright);
}

.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: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1rem 1.25rem;
}

.floating-session-timer {
    position: fixed;
    right: 1rem;
    bottom: 1rem;
    width: min(320px, calc(100% - 2rem));
    z-index: 102;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
}

.session-timer-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 0.75rem;
}

.session-title {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    color: var(--text-dim);
    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-code);
    border-radius: 999px;
    height: 8px;
    overflow: hidden;
}

.session-progress-bar {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, var(--green-bright), var(--green-dim));
    transition: width 0.3s ease;
}

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

.session-message {
    font-size: 0.8rem;
    color: var(--text-dim);
    font-style: italic;
    margin-top: 0.3rem;
    min-height: 1.2em;
    opacity: 0.7;
}

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

.session-controls {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.75rem;
}

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

.session-duration-select {
    background: var(--bg-card);
    color: var(--text-main);
    border: 1px solid var(--border);
    border-radius: 999px;
    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);
    color: var(--text-dim);
    padding: 0.35rem 0.75rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all 0.2s;
}

.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(--green-bright);
        border-color: var(--green-bright);
    }
    50% {
        box-shadow: 0 0 30px 10px var(--green-glow);
        border-color: var(--green-bright);
        transform: scale(1.02);
    }
    100% {
        box-shadow: 0 0 0 0 var(--green-glow);
        border-color: var(--border);
        transform: scale(1);
    }
}

@keyframes timer-pulse {
    0%, 100% {
        box-shadow: 0 0 0 rgba(230, 0, 18, 0.3);
    }
    50% {
        box-shadow: 0 0 20px rgba(230, 0, 18, 0.5);
    }
}

.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: var(--bg-card);
    border-right: 1px solid var(--border);
    overflow-y: auto;
    padding: 0 0 1rem;
    z-index: 100;
    transform: translateX(-100%);
    transition: transform 0.3s ease;
}

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

.sidebar-toggle {
    position: fixed;
    left: 1rem;
    top: 0.5rem;
    width: 40px;
    height: 40px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 6px;
    cursor: pointer;
    z-index: 101;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: var(--text-main);
    transition: all 0.3s ease;
}

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

/* When sidebar is open, 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);
    border-radius: 0;
}

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

.sidebar-header {
    padding: 0 1rem 0 3.5rem;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    border-bottom: 1px solid var(--border);
    margin-bottom: 0.5rem;
    min-height: 48px;
    display: flex;
    align-items: center;
}

.sidebar-header a {
    color: var(--green-bright);
    text-decoration: none;
    transition: color 0.2s;
}

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

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

.sidebar-sections {
    /* Nested sections under active module */
    margin-left: 1.5rem;
    padding-left: 0.75rem;
    border-left: 1px solid var(--border);
    margin-bottom: 0.5rem;
}

.sidebar-section-link {
    display: block;
    padding: 0.4rem 0.75rem;
    color: var(--text-dim);
    text-decoration: none;
    font-size: 0.75rem;
    transition: all 0.2s;
}

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

.sidebar-section-link.active {
    color: var(--cyan);
    font-weight: 500;
}



.sidebar-link {
    display: flex;
    align-items: center;
    padding: 0.5rem 1rem;
    color: var(--text-dim);
    text-decoration: none;
    font-size: 0.85rem;
    transition: all 0.2s;
    border-left: 3px solid transparent;
}

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

.sidebar-link.active {
    color: var(--green-bright);
    background: var(--bg-code);
    border-left-color: var(--green-bright);
}

.sidebar-module-num {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    opacity: 0.7;
    margin-right: 0.5rem;
}

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

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

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

/* Add top padding when sidebar toggle is present */
body.has-sidebar .container {
    padding-top: 4rem;
}

/* When sidebar is open on medium screens, shift content right */
@media (min-width: 901px) and (max-width: 1400px) {
    body.sidebar-open .container {
        margin-left: 300px;
        margin-right: 20px;
    }
}

/* On ultrawide screens, content stays centered - sidebar floats over empty space */

/* Mobile: full 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, 0.5);
        z-index: 99;
    }

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

/* ============================================
   17. Footer
   ============================================ */
footer {
    border-top: 1px solid var(--border);
    padding: 2rem 0;
    margin-top: 4rem;
    text-align: center;
    color: var(--text-dim);
    font-size: 0.9rem;
}

/* ============================================
   18. Visual Box, Quote Box, Concept Links
   ============================================ */
.visual-box {
    background: var(--bg-code);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 2rem;
    margin: 1.5rem 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
}

.concept-link {
    font-size: 0.75rem;
    text-decoration: none;
    transition: all 0.2s;
}

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

/* ============================================
   19. Responsive Adjustments
   ============================================ */
/* ============================================
   Exercise Progress Tracking
   ============================================ */
.exercise-completed {
    border-left: 4px solid var(--green-bright);
    position: relative;
}

.exercise-completed::after {
    content: '\2713';
    position: absolute;
    top: 1rem;
    right: 1rem;
    width: 24px;
    height: 24px;
    background: var(--green-bright);
    color: var(--bg-dark);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: 700;
}

.self-rating {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: 1rem;
    padding-top: 0.75rem;
    border-top: 1px solid var(--bg-lighter);
}

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

.rating-btn {
    background: transparent;
    border: 1px solid var(--bg-lighter);
    color: var(--text-dim);
    padding: 0.3rem 0.75rem;
    border-radius: 6px;
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all 0.2s;
}

.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-dark);
    font-weight: 600;
}

.rating-btn.active.struggled {
    background: var(--orange);
    border-color: var(--orange);
    color: var(--bg-dark);
    font-weight: 600;
}

.rating-btn.active.peeked {
    background: var(--purple);
    border-color: var(--purple);
    color: white;
    font-weight: 600;
}

/* Dashboard exercise progress */
.exercise-progress-inline {
    font-size: 0.75rem;
    color: var(--text-dim);
    font-family: 'JetBrains Mono', monospace;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.exercise-progress-fill {
    height: 100%;
    background: var(--green-bright);
    border-radius: 2px;
    transition: width 0.3s ease;
}

/* ============================================
   Solution Annotations
   ============================================ */
.solution-annotations {
    margin-top: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.annotation {
    display: flex;
    align-items: flex-start;
    gap: 0.6rem;
    padding: 0.5rem 0.75rem;
    border-radius: 6px;
    background: var(--bg-code);
    border-left: 3px solid var(--text-dim);
    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-lighter);
    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-dim);
    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: 1rem;
    }

    .module-header h1 {
        font-size: 2rem;
    }

    .nav-buttons {
        flex-direction: column;
        gap: 1rem;
    }

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

    .theme-picker {
        top: 0.5rem;
        right: 0.5rem;
        min-width: 0;
    }

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

    .theme-picker-label {
        font-size: 0.65rem;
    }
}

/* ============================================================
   Streak Section & Activity Heatmap
   ============================================================ */
.activity-heatmap {
    overflow-x: auto;
    padding: 0.5rem 0;
}

/* ============================================================
   Flashcard Styles
   ============================================================ */
.flashcard {
    perspective: 1000px;
    cursor: pointer;
    min-height: 250px;
}

.flashcard-inner {
    position: relative;
    width: 100%;
    min-height: 250px;
    transition: transform 0.5s ease;
    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-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    box-sizing: border-box;
}

.flashcard-front {
    border-left: 4px solid var(--cyan);
}

.flashcard-back {
    transform: rotateY(180deg);
    border-left: 4px solid var(--green-bright);
}

.flashcard-front code,
.flashcard-back code {
    background: var(--bg-code, var(--bg-lighter));
    padding: 0.15em 0.4em;
    border-radius: 4px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9em;
    color: var(--green-bright);
}

.fc-keyboard-hint {
    text-align: center;
    color: var(--text-dim);
    font-size: 0.8rem;
    margin-top: 1rem;
}

.fc-keyboard-hint kbd {
    background: var(--bg-lighter);
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 0.1em 0.4em;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85em;
}

/* ============================================================
   Shared Button Styles (Quick Buttons, Option Buttons)
   ============================================================ */
.quick-btn {
    padding: 1rem 1.5rem;
    background: var(--bg-card);
    border: 2px solid var(--bg-lighter);
    border-radius: 8px;
    text-align: center;
    text-decoration: none;
    color: var(--text);
    transition: all 0.2s;
    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(--orange);
    transform: translateY(-2px);
}

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

.quick-btn.primary:hover {
    background: #fff;
}


/* ============================================================
   Shared Option Button Styles (Daily Practice, Flashcards)
   ============================================================ */
.dp-option {
    background: transparent;
    border: 2px solid var(--bg-lighter);
    color: var(--text);
    padding: 0.4rem 1rem;
    border-radius: 6px;
    font-size: 0.85rem;
    font-family: 'JetBrains Mono', monospace;
    cursor: pointer;
    transition: all 0.2s;
}

.dp-option:hover {
    border-color: var(--orange);
}

.dp-option.active {
    background: var(--orange);
    border-color: var(--orange);
    color: white;
    font-weight: 600;
}

/* ============================================================
   Analytics / Weak Concept Styles
   ============================================================ */
.strength-bar {
    height: 8px;
    border-radius: 4px;
    background: var(--bg-lighter);
    overflow: hidden;
}

.strength-fill {
    height: 100%;
    border-radius: 4px;
}

.analytics-drill-btn {
    display: inline-block;
    font-size: 0.75rem;
    padding: 0.2rem 0.6rem;
    border: 1px solid var(--orange);
    border-radius: 4px;
    color: var(--orange);
    text-decoration: none;
    font-family: 'JetBrains Mono', monospace;
    transition: background 0.2s, color 0.2s;
    white-space: nowrap;
}

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

/* ============================================================
   Dashboard Page Styles
   ============================================================ */
.dashboard-header {
    margin: 2rem 0 2.5rem;
}

/* Dashboard Panel */
.dashboard-panel {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1rem 1.25rem;
    margin-bottom: 1rem;
}
.panel-actions {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}
.resume-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 1.25rem;
    background: var(--green-bright);
    color: var(--bg-dark);
    border-radius: 999px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    font-weight: 700;
    text-decoration: none;
    transition: all 0.2s;
    white-space: nowrap;
}
.resume-btn:hover {
    background: #fff;
    opacity: 1;
}
.panel-actions .session-controls {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: 0;
}
.dashboard-panel .session-duration {
    width: auto;
    padding: 0.45rem 0.7rem;
    border-radius: 999px;
    font-size: 0.8rem;
}
.dashboard-panel .session-start-btn {
    padding: 0.45rem 1rem;
    border-radius: 999px;
    font-size: 0.8rem;
}
.panel-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    padding-top: 0.75rem;
    margin-top: 0.75rem;
    border-top: 1px solid var(--border);
}
.nav-pill {
    padding: 0.3rem 0.85rem;
    border: 1px solid var(--border);
    border-radius: 999px;
    font-size: 0.8rem;
    color: var(--text-dim);
    text-decoration: none;
    font-family: 'JetBrains Mono', monospace;
    transition: all 0.2s;
}
.nav-pill:hover {
    border-color: var(--orange);
    color: var(--orange);
    opacity: 1;
}

/* Stats Panel */
.stats-panel {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 1rem 1.25rem;
    margin-bottom: 2rem;
}
.stats-row {
    display: flex;
    justify-content: space-around;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border);
}
.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-panel .stat-value {
    font-size: 1.5rem;
}
.stats-panel .stat-label {
    margin-top: 0.25rem;
}
.stats-panel #activity-heatmap {
    padding-top: 0.75rem;
    border-top: 1px solid var(--border);
    margin-top: 0.25rem;
    display: flex;
    justify-content: center;
}

/* Data management buttons */
.data-btn {
    padding: 0.5rem 1rem;
    background: transparent;
    border: 1px solid var(--bg-lighter);
    color: var(--text-dim);
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    transition: all 0.2s;
}
.data-btn:hover {
    border-color: var(--orange);
    color: var(--orange);
}

@media (max-width: 720px) {
    .panel-actions {
        flex-direction: column;
        align-items: stretch;
        gap: 0.75rem;
    }
    .resume-btn {
        justify-content: center;
    }
    .panel-actions .session-controls {
        justify-content: center;
    }
}
@media (max-width: 480px) {
    .stats-row {
        flex-wrap: wrap;
        gap: 0.5rem;
    }
    .stat-item {
        min-width: 80px;
    }
}
.session-start-btn {
    padding: 0.65rem 1.25rem;
    background: var(--green-bright);
    border: 2px solid var(--green-bright);
    border-radius: 8px;
    color: var(--bg-dark);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s;
    white-space: nowrap;
}
.session-start-btn:hover {
    background: #fff;
}
.session-duration {
    width: 100%;
    padding: 0.65rem 0.9rem;
    border-radius: 8px;
    border: 2px solid var(--bg-lighter);
    background: var(--bg-card);
    color: var(--text);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
}

.session-timer {
    margin-bottom: 2rem;
}
.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-dim);
    margin-top: 0.5rem;
}
.module-list {
    margin-top: 2rem;
}
.track-section {
    margin: 2rem 0;
}
.track-title {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-dim);
    margin-bottom: 1rem;
    font-weight: 600;
}
.module-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    background: var(--bg-card);
    border: 1px solid var(--bg-lighter);
    border-radius: 6px;
    margin-bottom: 0.5rem;
    transition: all 0.2s;
}
.module-item:hover {
    border-color: var(--orange);
}
.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: 1rem;
}
.module-num {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    color: var(--text-dim);
    min-width: 80px;
}
.module-name {
    font-weight: 500;
}
.module-item.completed {
    opacity: 0.6;
}
.module-item.completed .module-name {
    text-decoration: line-through;
}
.last-studied {
    font-size: 0.75rem;
    color: var(--text-dim);
    font-family: 'JetBrains Mono', monospace;
}
.clear-progress {
    padding: 0.5rem 1rem;
    background: transparent;
    border: 1px solid var(--bg-lighter);
    color: var(--text-dim);
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    transition: all 0.2s;
}
.clear-progress:hover {
    border-color: var(--orange);
    color: var(--orange);
}
.export-notes {
    padding: 0.5rem 1rem;
    background: transparent;
    border: 1px solid var(--purple);
    color: var(--purple);
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    transition: all 0.2s;
}
.export-notes:hover {
    background: var(--purple);
    color: var(--bg-dark);
}
.data-management {
    margin-top: 2rem;
}
.data-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}
.clear-progress--danger {
    border-color: var(--red);
    color: var(--red);
}