/* ===================================
   CSS Variables - Easy Theme Switching
   =================================== */
:root {
    /* Colors */
    --primary-blue: #0f4761;
    --secondary-blue: #1a7ba4;
    --accent-blue: #2d7a8f;
    --text-dark: #2c3e50;
    --text-light: #5a6c7d;
    --bg-white: #ffffff;
    --bg-light: #f8f9fa;
    --bg-code: #2d2d2d;
    --border-color: #e1e8ed;
    --success-green: #28a745;

    /* Spacing */
    --max-width: 1400px;
    --header-height: 130px;
    --header-height-scrolled: 60px;
    --sidebar-width: 280px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* Typography */
    --font-body: 'Play', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'Roboto Mono', 'Consolas', 'Monaco', 'Courier New', monospace;
    --font-size-base: 16px;
    --line-height-base: 1.6;
}

/* ===================================
   Dark Theme
   =================================== */
[data-theme="dark"] {
    /* Background & Surface Colors */
    --bg-white: #1e1e1e;
    --bg-light: #252526;
    --bg-code: #2d2d2d;

    /* Text Colors */
    --text-dark: #d4d4d4;
    --text-light: #9ca3af;

    /* Blue Accent Colors */
    --primary-blue: #569cd6;
    --secondary-blue: #4fc3f7;
    --accent-blue: #64b5f6;

    /* Other Colors */
    --border-color: #3e3e42;
    --success-green: #4caf50;
}

/* Dark theme - specific overrides for elements that need special handling */
[data-theme="dark"] .site-header {
    background: linear-gradient(135deg, #2a2a2a 0%, #1e1e1e 100%);
}

[data-theme="dark"] .theme-toggle {
    background: rgba(37, 37, 38, 0.9);
    border-color: var(--border-color);
}

[data-theme="dark"] .theme-toggle:hover {
    background: var(--bg-light);
    border-color: var(--primary-blue);
}

[data-theme="dark"] .toc-nav a:hover,
[data-theme="dark"] .toc-nav a.active {
    background: var(--bg-light);
}

[data-theme="dark"] .toc-nav li.toc-highlight a {
    background: #2a3a2a;
    border-left-color: #81c784;
    color: #81c784;
}

[data-theme="dark"] .toc-nav li.toc-highlight a:hover {
    background: #344834;
}

[data-theme="dark"] .back-to-top {
    background: var(--bg-light);
    border: 2px solid var(--border-color);
}

[data-theme="dark"] .back-to-top:hover {
    background: var(--primary-blue);
    border-color: var(--primary-blue);
}

/* Dark theme - Course cards and Lab list hover fixes */
[data-theme="dark"] .course-card {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

[data-theme="dark"] .course-card:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.5);
}

[data-theme="dark"] .lab-list a:hover {
    background: var(--bg-white);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

/* ===================================
   Global Resets & Base Styles
   =================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--text-dark);
    background-color: var(--bg-light);
}

/* ===================================
   Header
   =================================== */
.site-header {
    background: linear-gradient(135deg, #e8f1f5 0%, #f0f4f8 100%);
    padding: var(--spacing-md) var(--spacing-lg);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    width: 100%;
    z-index: 1000;
}

.header-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.header-logo {
    height: 53px;
    width: auto;
    display: block;
    margin-bottom: var(--spacing-sm);
}

.header-titles {
    text-align: center;
}

.header-subtitle {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 0.25rem;
}

.header-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-blue);
    margin: 0;
}

/* Scrolled state - no transitions, just instant changes */
.site-header.scrolled {
    padding: var(--spacing-sm) var(--spacing-lg);
}

.site-header.scrolled .header-logo {
    display: none;
}

.site-header.scrolled .header-subtitle {
    display: none;
}

.site-header.scrolled .header-title {
    font-size: 1.1rem;
}

/* Theme Toggle Button */
.theme-toggle {
    position: absolute;
    right: var(--spacing-lg);
    top: 50%;
    transform: translateY(-50%);
    background: rgba(255, 255, 255, 0.9);
    border: 2px solid var(--border-color);
    border-radius: 50%;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 1.5rem;
    z-index: 10;
}

.theme-toggle:hover {
    background: var(--bg-white);
    border-color: var(--primary-blue);
    transform: translateY(-50%) scale(1.1);
}

.theme-toggle:focus {
    outline: 2px solid var(--primary-blue);
    outline-offset: 2px;
}

.theme-toggle-icon {
    width: 24px;
    height: 24px;
    display: block;
    transition: transform 0.3s ease;
}

.theme-toggle:hover .theme-toggle-icon {
    transform: rotate(20deg);
}

/* Header spacer - takes up space in document flow for fixed header */
.header-spacer {
    height: calc(var(--header-height) + var(--spacing-xl));
}

/* Keep spacer the same height when scrolled - DON'T shrink it */

/* ===================================
   Container Layout
   =================================== */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-lg);
    display: flex;
    gap: var(--spacing-lg);
    align-items: flex-start;
}

/* ===================================
   Main Content
   =================================== */
.main-content {
    flex: 1;
    min-width: 0;
    display: flex;
    justify-content: center;
}

.content-wrapper {
    background: var(--bg-white);
    padding: var(--spacing-xl);
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    max-width: 1000px;
    width: 100%;
}

/* ===================================
   Table of Contents Sidebar
   =================================== */
.toc-sidebar {
    width: var(--sidebar-width);
    flex-shrink: 0;
    position: sticky;
    top: calc(var(--header-height) + var(--spacing-md));
    max-height: calc(100vh - var(--header-height) - var(--spacing-xl));
    overflow-y: auto;
    background: var(--bg-white);
    border-radius: 8px;
    padding: var(--spacing-md);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.toc-header h3 {
    color: var(--primary-blue);
    font-size: 1.1rem;
    margin-bottom: var(--spacing-sm);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border-color);
}

.toc-nav {
    font-size: 0.9rem;
}

.toc-nav ul {
    list-style: none;
    padding-left: 0;
}

.toc-nav li {
    margin: var(--spacing-xs) 0;
}

.toc-nav a {
    color: var(--text-light);
    text-decoration: none;
    display: block;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 4px;
    transition: all 0.2s ease;
    white-space: normal;
    word-break: break-word;
    line-height: 1.4;
}

.toc-nav a:hover {
    color: var(--secondary-blue);
    background: var(--bg-light);
}

.toc-nav a.active {
    color: var(--primary-blue);
    background: var(--bg-light);
    font-weight: 600;
    border-left: 3px solid var(--primary-blue);
}

/* Nested TOC items */
.toc-nav ul ul {
    padding-left: var(--spacing-md);
    margin-top: var(--spacing-xs);
}

.toc-nav ul ul a {
    font-size: 0.85rem;
}

/* Ensure code tags in TOC (if any) don't cause wrapping issues */
.toc-nav code {
    background: none;
    padding: 0;
    font-size: inherit;
    display: inline;
    white-space: nowrap;
}

/* Highlighted TOC entries (e.g., download sections) */
.toc-nav li.toc-highlight a {
    background: #fff9c4;
    border-left: 3px solid #f9a825;
    font-weight: 500;
}

.toc-nav li.toc-highlight a:hover {
    background: #fff59d;
}

/* ===================================
   Typography - Content
   =================================== */

.content-wrapper h1 {
    color: var(--primary-blue);
    font-size: 2.5rem;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 3px solid var(--primary-blue);
}

.content-wrapper h2 {
    color: var(--primary-blue);
    font-size: 2rem;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-xs);
    border-bottom: 3px solid var(--primary-blue);
}

.content-wrapper h3 {
    color: var(--secondary-blue);
    font-size: 1.5rem;
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

.content-wrapper h4 {
    color: var(--accent-blue);
    font-size: 1.25rem;
    margin-top: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
}

/* Hide horizontal rules immediately before headings */
/* Headings already have borders/visual separation, making the hr redundant */
.content-wrapper hr:has(+ h2),
.content-wrapper hr:has(+ h3),
.content-wrapper hr:has(+ h4) {
    display: none;
}

.content-wrapper p {
    margin-bottom: var(--spacing-md);
}

.content-wrapper a {
    color: var(--secondary-blue);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s ease;
}

.content-wrapper a:hover {
    border-bottom-color: var(--secondary-blue);
}

/* Mark/Highlight styling */
.content-wrapper mark {
    background-color: #fff3cd;
    color: #856404;
    padding: 0.1em 0.3em;
    border-radius: 3px;
}

[data-theme="dark"] .content-wrapper mark {
    background-color: #4a4a2a;
    color: #ffd700;
}

/* ===================================
   Lists
   =================================== */
.content-wrapper ul,
.content-wrapper ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-lg);
}

.content-wrapper li {
    margin-bottom: var(--spacing-xs);
}

/* ===================================
   Code Blocks
   =================================== */
.content-wrapper code {
    font-family: var(--font-mono);
    font-size: 0.95em;
    background: var(--bg-light);
    padding: 2px 6px;
    border-radius: 3px;
    color: var(--accent-blue);
}

.content-wrapper pre {
    position: relative;
    background: var(--bg-code);
    border: 1px solid #1a1a1a;
    border-radius: 8px;
    overflow-x: auto;
    overflow-y: visible;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    padding: var(--spacing-md) var(--spacing-lg);
}

/* Code styling inside pre */
.content-wrapper pre code {
    background: transparent;
    color: #f8f8f2;
    display: block;
    line-height: 1.5;
    font-size: 1em;
}

/* Word wrapping - only for code blocks marked with 'wrap' keyword */
.content-wrapper pre.code-wrap code,
.content-wrapper pre.code-wrap code[class*="language-"] {
    white-space: pre-wrap !important;       /* Enable word wrapping */
    word-break: break-word;                  /* Break long words if needed */
}

/* Default: no word wrap for code blocks with line numbers */
.content-wrapper pre.line-numbers code {
    white-space: pre;                        /* Keep default for line-numbered code */
}

pre.line-numbers code {
    padding-left: 1em;
}

pre.line-numbers > .line-numbers-rows {
    margin-top: 0.18em !important;
}

/* Prism line-numbers gutter fix */
pre.line-numbers {
    padding-left: calc(var(--spacing-lg) + 3.8em);
}

/* Override Prism line numbers to be visible on dark background */
.line-numbers .line-numbers-rows {
    border-right-color: #4a4a4a !important;
}

.line-numbers .line-numbers-rows > span:before {
    color: #999 !important;
}

/* Spacing fix: Add extra top margin to content that follows code blocks */
/* This prevents introductory text from appearing too close to the code block above it */
.content-wrapper pre + * {
    margin-top: var(--spacing-lg); /* 2rem - creates clear visual separation */
}

/* Exception: Keep normal spacing between consecutive code blocks */
.content-wrapper pre + pre,
.content-wrapper pre + .code-preview {
    margin-top: var(--spacing-md); /* 1.5rem - normal spacing */
}

/* Code preview output box */
.code-preview {
    margin: var(--spacing-md) 0 var(--spacing-lg) 0;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: var(--spacing-md);
    background: var(--bg-white);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.05);
}

.code-preview-label {
    font-size: 0.85rem;
    color: var(--text-light);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Reset all custom styles inside preview - show browser defaults only */
.code-preview iframe {
    width: 100%;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-white);
    min-height: 80px;
    display: block;
}

/* ===================================
   Blockquotes
   =================================== */
.content-wrapper blockquote {
    border-left: 4px solid var(--primary-blue);
    background: var(--bg-light);
    padding: var(--spacing-md);
    margin: var(--spacing-md) 0;
    font-style: italic;
    color: var(--text-light);
}

/* ===================================
   Array/List Diagram
   =================================== */
.array-diagram {
    margin: var(--spacing-lg) 0;
    overflow-x: auto;
    display: inline-block;
}

.array-diagram .array-label {
    font-family: 'Roboto Mono', monospace;
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--text-dark);
    margin-bottom: 0.4rem;
}

.array-diagram table {
    border-collapse: collapse;
}

.array-diagram .array-cells td {
    min-width: 52px;
    padding: 0.5rem 0.75rem;
    text-align: center;
    font-family: 'Roboto Mono', monospace;
    font-weight: 600;
    font-size: 1rem;
    color: #1565c0;
    background: #e3f2fd;
    border: 2px solid #1565c0;
}

.array-diagram .array-indexes td {
    padding: 0.3rem 0.75rem;
    text-align: center;
    font-family: 'Roboto Mono', monospace;
    font-size: 1rem;
    color: var(--text-light);
    border: none;
}

/* Highlighted cell (for traversal snapshots) */
.array-diagram .array-cells td.highlight {
    background: #fff9c4;
    color: #e65100;
    outline: 2px solid #e65100;
    outline-offset: -2px;
}

.array-diagram .array-indexes td.highlight {
    color: #e65100;
    font-weight: 600;
}

.array-diagram .array-annotation {
    font-family: 'Roboto Mono', monospace;
    font-size: 0.95rem;
    color: #e65100;
    margin-top: 0.3rem;
}

/* Error cell (out-of-bounds access) */
.array-diagram .array-cells td.error {
    background: #ffebee;
    color: #c62828;
    border: 2px dashed #c62828;
}

.array-diagram .array-indexes td.error {
    color: #c62828;
    font-weight: 600;
}

.array-diagram .array-annotation.error {
    color: #c62828;
}

/* Dark theme - Array diagram */
[data-theme="dark"] .array-diagram .array-label {
    color: #d4d4d4;
}

[data-theme="dark"] .array-diagram .array-cells td {
    color: #90caf9;
    background: #1a2a3a;
    border-color: #64b5f6;
}

[data-theme="dark"] .array-diagram .array-indexes td {
    color: #999;
}

[data-theme="dark"] .array-diagram .array-cells td.highlight {
    background: #3e2c0a;
    color: #ffb74d;
    outline: 2px solid #ffb74d;
    outline-offset: -2px;
}

[data-theme="dark"] .array-diagram .array-indexes td.highlight {
    color: #ffb74d;
}

[data-theme="dark"] .array-diagram .array-annotation {
    color: #ffb74d;
}

[data-theme="dark"] .array-diagram .array-cells td.error {
    background: #3a1a1a;
    color: #ef9a9a;
    border-color: #ef9a9a;
}

[data-theme="dark"] .array-diagram .array-indexes td.error {
    color: #ef9a9a;
}

[data-theme="dark"] .array-diagram .array-annotation.error {
    color: #ef9a9a;
}

/* ===================================
   Note Box (informational callout)
   =================================== */
.content-wrapper .note-box {
    background: linear-gradient(135deg, #e3f2fd 0%, #e8eaf6 100%);
    border: 2px solid #64b5f6;
    border-radius: 8px;
    padding: var(--spacing-md) var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    color: #333;
}

.content-wrapper .note-box p {
    margin: 0;
    font-size: 0.95rem;
    line-height: 1.6;
}

.content-wrapper .note-box p + p {
    margin-top: var(--spacing-sm);
}

.content-wrapper .note-box strong {
    color: #1565c0;
}

.content-wrapper .note-box code {
    background: rgba(255, 255, 255, 0.6);
}

/* Dark theme - Note box */
[data-theme="dark"] .content-wrapper .note-box {
    background: linear-gradient(135deg, #1a2233 0%, #1a1f2e 100%);
    border-color: #4a7ab5;
    color: #d4d4d4;
}

[data-theme="dark"] .content-wrapper .note-box strong {
    color: #64b5f6;
}

[data-theme="dark"] .content-wrapper .note-box code {
    background: rgba(0, 0, 0, 0.3);
}

/* ===================================
   Download/Assets Box
   =================================== */
.content-wrapper .download-box {
    background: linear-gradient(135deg, #e8f5e9 0%, #f1f8e9 100%);
    border: 2px solid #81c784;
    border-radius: 8px;
    padding: var(--spacing-md) var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    color: #333;
}

.content-wrapper .download-box h3 {
    color: #2e7d32;
    margin: 0 0 var(--spacing-sm) 0;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    border-bottom: none;
    padding-bottom: 0;
}

.content-wrapper .download-box h3::before {
    content: "\2913";
    font-size: 1.3rem;
}

.content-wrapper .download-box ul {
    margin: 0;
    padding-left: 0;
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.content-wrapper .download-box li {
    margin: 0;
}

.content-wrapper .download-box a.download-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: #2e7d32;
    color: white;
    padding: 0.4rem 0.75rem;
    border-radius: 4px;
    text-decoration: none;
    font-weight: 500;
    font-size: 0.85rem;
    transition: background 0.2s ease;
}

.content-wrapper .download-box a.download-btn:hover {
    background: #1b5e20;
}

.content-wrapper .download-box a.download-btn::before {
    content: "\2193";
    font-weight: bold;
}

.content-wrapper .download-box p {
    margin: var(--spacing-sm) 0 0 0;
    font-size: 0.9rem;
    color: #558b2f;
}

/* Dark theme - Download box */
[data-theme="dark"] .content-wrapper .download-box {
    background: linear-gradient(135deg, #1a2e1a 0%, #1e2e1a 100%);
    border-color: #4a7a4a;
    color: #d4d4d4;
}

[data-theme="dark"] .content-wrapper .download-box h3 {
    color: #81c784;
}

[data-theme="dark"] .content-wrapper .download-box a.download-btn {
    background: #2e7d32;
}

[data-theme="dark"] .content-wrapper .download-box a.download-btn:hover {
    background: #388e3c;
}

[data-theme="dark"] .content-wrapper .download-box p {
    color: #81c784;
}

/* ===================================
   Video Box
   =================================== */
.content-wrapper a.video-box {
    display: block;
    background: linear-gradient(135deg, #fce4ec 0%, #ffebee 100%);
    border: 2px solid #e57373;
    border-radius: 8px;
    padding: var(--spacing-md) var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    color: #333;
    text-decoration: none;
    cursor: pointer;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.content-wrapper a.video-box:hover {
    border-color: #c62828;
    box-shadow: 0 2px 8px rgba(198, 40, 40, 0.2);
}

.content-wrapper a.video-box h3 {
    color: #c62828;
    margin: 0 0 var(--spacing-sm) 0;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    border-bottom: none;
    padding-bottom: 0;
}

.content-wrapper a.video-box h3::before {
    content: "\25B6";
    font-size: 1rem;
}

.content-wrapper a.video-box p {
    margin: var(--spacing-sm) 0 0 0;
    font-size: 0.9rem;
    color: #b71c1c;
}

/* Dark theme - Video box */
[data-theme="dark"] .content-wrapper a.video-box {
    background: linear-gradient(135deg, #2e1a1a 0%, #2e1c1c 100%);
    border-color: #7a4a4a;
    color: #d4d4d4;
}

[data-theme="dark"] .content-wrapper a.video-box:hover {
    border-color: #ef9a9a;
    box-shadow: 0 2px 8px rgba(239, 154, 154, 0.15);
}

[data-theme="dark"] .content-wrapper a.video-box h3 {
    color: #ef9a9a;
}

[data-theme="dark"] .content-wrapper a.video-box p {
    color: #ef9a9a;
}

/* ===================================
   Attention/Notice Box
   =================================== */
.content-wrapper .attention-box {
    background: linear-gradient(135deg, #fff3e0 0%, #ffe0b2 100%);
    border: 2px solid #ff9800;
    border-radius: 8px;
    padding: var(--spacing-md) var(--spacing-lg);
    margin: var(--spacing-md) 0;
}

.content-wrapper .attention-box p {
    margin: 0;
    color: #e65100;
    font-weight: 600;
    font-size: 0.95rem;
}

/* ===================================
   Highlighted/Mark Text
   =================================== */
.content-wrapper mark {
    background-color: #ffeb3b;
    color: var(--text-dark);
    padding: 2px 4px;
    border-radius: 2px;
}

/* ===================================
   Tables
   =================================== */
.content-wrapper table:not(.code-preview table) {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: var(--spacing-md);
}

.content-wrapper th:not(.code-preview th) {
    background: var(--primary-blue);
    color: white;
    padding: var(--spacing-sm);
    text-align: left;
    font-weight: 600;
}

.content-wrapper td:not(.code-preview td) {
    padding: var(--spacing-sm);
    border-bottom: 1px solid var(--border-color);
}

.content-wrapper tr:not(.code-preview tr):hover {
    background: var(--bg-light);
}

/* ===================================
   Images
   =================================== */
.content-wrapper img {
    max-width: 100%;
    height: auto;
    border-radius: 6px;
    margin: var(--spacing-md) 0;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.content-wrapper figure {
    margin: var(--spacing-md) 0;
    text-align: center;
}

.content-wrapper figure img {
    margin: 0;
}

.content-wrapper figcaption {
    margin-top: 6px;
    font-style: italic;
}

.content-wrapper figure.video-demo video {
    width: 280px;
    max-width: 100%;
    height: auto;
    border-radius: 6px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

/* ===================================
   Loading State
   =================================== */
.loading {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--text-light);
    font-style: italic;
}

/* ===================================
   Footer
   =================================== */
.site-footer {
    background: var(--primary-blue);
    color: white;
    text-align: center;
    padding: var(--spacing-md);
    margin-top: var(--spacing-xl);
}

.site-footer p {
    margin: 0;
    font-size: 0.9rem;
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 1024px) {
    .container {
        flex-direction: column;
    }

    .toc-sidebar {
        width: 100%;
        position: static;
        max-height: none;
        margin-bottom: var(--spacing-md);
    }
}

@media (max-width: 768px) {
    .header-title {
        font-size: 1.25rem;
    }

    .header-logo {
        height: 40px;
    }

    .content-wrapper {
        padding: var(--spacing-md);
    }

    .content-wrapper h1 {
        font-size: 2rem;
    }

    .content-wrapper h2 {
        font-size: 1.5rem;
    }

    .container {
        padding: var(--spacing-sm);
    }
}

/* ===================================
   Scrollbar Styling (Webkit browsers)
   =================================== */
.toc-sidebar::-webkit-scrollbar {
    width: 6px;
}

.toc-sidebar::-webkit-scrollbar-track {
    background: var(--bg-light);
}

.toc-sidebar::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

.toc-sidebar::-webkit-scrollbar-thumb:hover {
    background: var(--text-light);
}

/* ===================================
   Breadcrumbs
   =================================== */
.breadcrumbs {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 0.9rem;
    color: var(--text-light);
}

.breadcrumbs a {
    color: var(--secondary-blue);
    text-decoration: none;
    transition: color 0.2s ease;
}

.breadcrumbs a:hover {
    color: var(--primary-blue);
    text-decoration: underline;
}

.breadcrumb-separator {
    color: var(--text-light);
    margin: 0 0.5rem;
}

.breadcrumb-current {
    color: var(--text-dark);
    font-weight: 600;
}

/* ===================================
   Home Page
   =================================== */
.home-page {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-lg);
}

.home-content {
    text-align: center;
}

.home-content h1 {
    color: var(--primary-blue);
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
}

.home-description {
    font-size: 1.1rem;
    color: var(--text-light);
    margin-bottom: var(--spacing-xl);
}

.course-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    max-width: 800px;
    margin: 0 auto;
}

.course-card {
    background: var(--bg-white);
    border-radius: 8px;
    padding: var(--spacing-xl);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.course-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.course-card h2 {
    color: var(--primary-blue);
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
}

.course-card p {
    color: var(--text-light);
    margin-bottom: var(--spacing-md);
}

.card-button {
    display: inline-block;
    background: var(--secondary-blue);
    color: white;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: 4px;
    text-decoration: none;
    font-weight: 600;
    transition: background 0.2s ease;
}

.card-button:hover {
    background: var(--primary-blue);
}

/* ===================================
   Lab List Page
   =================================== */
.lab-list-page {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-lg);
}

.lab-list-content {
    background: var(--bg-white);
    border-radius: 8px;
    padding: var(--spacing-xl);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    max-width: 800px;
    margin: 0 auto;
}

.lab-list-content h1 {
    color: var(--primary-blue);
    font-size: 2rem;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-sm);
    border-bottom: 3px solid var(--primary-blue);
}

.lab-list {
    list-style: none;
    padding: 0;
}

.lab-list li {
    margin-bottom: var(--spacing-md);
}

.lab-list a {
    display: block;
    padding: var(--spacing-md);
    background: var(--bg-light);
    border-radius: 6px;
    text-decoration: none;
    transition: all 0.2s ease;
    border-left: 4px solid var(--secondary-blue);
}

.lab-list a:hover {
    background: white;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    border-left-color: var(--primary-blue);
    transform: translateX(4px);
}

/* Solutions link styling */
.lab-list li.lab-solutions {
    margin-top: calc(var(--spacing-md) * -0.5);
    margin-bottom: var(--spacing-md);
}

.lab-list li.lab-solutions a {
    margin-left: var(--spacing-lg);
    padding: calc(var(--spacing-md) * 0.75) var(--spacing-md);
    background: var(--bg-light);
    border-left: 3px solid var(--accent-blue);
    font-size: 0.9rem;
    opacity: 0.9;
}

.lab-list li.lab-solutions a:hover {
    background: var(--bg-white);
    border-left-color: var(--secondary-blue);
    opacity: 1;
    transform: translateX(4px);
}

.lab-list li.lab-solutions .lab-title {
    color: var(--text-light);
}

.lab-number {
    font-weight: 700;
    color: var(--primary-blue);
    margin-right: var(--spacing-sm);
}

.lab-title {
    color: var(--text-dark);
}

.lab-note {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-style: italic;
    margin-top: 0.25rem;
    padding-left: calc(var(--spacing-sm) + 0.5rem);
}

/* ===================================
   Back to Top Button
   =================================== */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 50px;
    height: 50px;
    background: var(--secondary-blue);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease, background 0.2s ease, transform 0.2s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    z-index: 999;
}

.back-to-top:hover {
    background: var(--primary-blue);
    transform: translateY(-3px);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.3);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

/* ===================================
   Responsive - Home and Lab List
   =================================== */
@media (max-width: 768px) {
    .home-content h1 {
        font-size: 2rem;
    }

    .course-cards {
        grid-template-columns: 1fr;
    }

    .breadcrumbs {
        font-size: 0.8rem;
        padding: var(--spacing-xs) var(--spacing-sm);
    }

    .back-to-top {
        bottom: 1rem;
        right: 1rem;
        width: 45px;
        height: 45px;
        font-size: 1.3rem;
    }
}

/* Copy button for code blocks */
.copy-btn {
    position: absolute;
    top: 10px;
    right: 10px;
    padding: 4px 10px;
    font-size: 0.75rem;
    font-family: 'Roboto Mono', monospace;
    background: rgba(255, 255, 255, 0.15);
    color: #bbb;
    border: 1px solid rgba(255, 255, 255, 0.25);
    border-radius: 4px;
    cursor: pointer;
    z-index: 1;
    transition: background 0.2s, color 0.2s;
}

.copy-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    color: #ccc;
}

.copy-btn.copied {
    background: rgba(76, 175, 80, 0.3);
    color: #81c784;
    border-color: rgba(76, 175, 80, 0.4);
}