/* ============================================
   MySQL Mastery - Premium Documentation Style
   Color Palette: Primary #2E77AE, Dark #0D2137, Light #E0EAF5, Accent #FF8E2B
   ============================================ */

/* Import Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;500&family=Inter:wght@300;400;500;600;700&display=swap');

/* CSS Variables - Brand & System Colors */
:root {
    /* Brand Colors */
    --color-primary: #2E77AE;
    --color-primary-dark: #1E5A8A;
    --color-primary-light: #4A9BD9;
    --color-primary-transparent: rgba(46, 119, 174, 0.1);

    --color-dark-bg: #0D2137;
    --color-dark-surface: #152A42;

    --color-light-bg: #F8FAFC;
    --color-light-surface: #FFFFFF;

    --color-accent: #FF8E2B;
    --color-accent-dark: #E67A1F;
    --color-accent-transparent: rgba(255, 142, 43, 0.15);

    /* System Colors - Light Mode Default */
    --bg-body: var(--color-light-bg);
    --bg-surface: var(--color-light-surface);
    --bg-sidebar: #0B1C2E;
    /* Slightly darker than brand dark for contrast */
    --bg-code: #1E293B;
    /* Slate 800 */
    --bg-code-inline: #F1F5F9;

    --text-primary: #1E293B;
    /* Slate 800 */
    --text-secondary: #475569;
    /* Slate 600 */
    --text-tertiary: #94A3B8;
    /* Slate 400 */
    --text-inverse: #F8FAFC;

    --border-color: #E2E8F0;
    --border-focus: var(--color-primary-light);

    /* Functional Colors */
    --info-bg: #F0F9FF;
    --info-border: #0EA5E9;
    --info-text: #0C4A6E;

    --warning-bg: #FFFBEB;
    --warning-border: #F59E0B;
    --warning-text: #92400E;

    --success-bg: #F0FDF4;
    --success-border: #10B981;
    --success-text: #065F46;

    --danger-bg: #FEF2F2;
    --danger-border: #EF4444;
    --danger-text: #991B1B;

    /* Metrics */
    --header-height: 64px;
    --sidebar-width: 280px;
    --toc-width: 250px;
    --content-max-width: 960px;

    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;

    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

/* Dark Mode Overrides */
[data-theme="dark"] {
    --bg-body: #0A1625;
    --bg-surface: #112236;
    --bg-sidebar: #050E1A;
    --bg-code: #020617;
    /* Very dark slate */
    --bg-code-inline: #1E293B;

    --text-primary: #F1F5F9;
    --text-secondary: #CBD5E1;
    --text-tertiary: #64748B;
    --text-inverse: #0F172A;

    --border-color: #1E293B;

    --info-bg: rgba(14, 165, 233, 0.1);
    --info-text: #BAE6FD;

    --warning-bg: rgba(245, 158, 11, 0.1);
    --warning-text: #FDE68A;

    --success-bg: rgba(16, 185, 129, 0.1);
    --success-text: #6EE7B7;

    --danger-bg: rgba(239, 68, 68, 0.1);
    --danger-text: #FCA5A5;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
    height: 100%;
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-body);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    height: 100%;

    /* Subtle Grid Pattern */
    background-image:
        radial-gradient(var(--border-color) 1px, transparent 1px);
    background-size: 32px 32px;
    background-position: 0 0;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--text-tertiary);
    border-radius: 4px;
    border: 2px solid transparent;
    background-clip: content-box;
}

::-webkit-scrollbar-thumb:hover {
    background-color: var(--text-secondary);
}

/* Grid Layout System */
.layout-container {
    display: grid;
    grid-template-columns: var(--sidebar-width) minmax(0, 1fr) var(--toc-width);
    grid-template-areas: "sidebar content toc";
    width: 100%;
    max-width: 100%;
    margin: 0 auto;
    gap: 0;
    position: relative;
    padding-top: var(--header-height);
}

/* Sidebar Column */
.sidebar {
    grid-area: sidebar;
    width: var(--sidebar-width);
    position: sticky;
    top: var(--header-height);
    height: calc(100vh - var(--header-height));
    overflow-y: auto;
    border-right: 1px solid var(--border-color);
    background-color: var(--bg-sidebar);
    z-index: 50;
    transition: transform 0.3s ease;
}

/* Main Content Column */
.main-content-wrapper {
    grid-area: content;
    width: 100%;
    min-width: 0;
    /* Crucial for preventing grid blowout */
    display: flex;
    justify-content: center;
    margin: 0;
}

.main-content {
    width: 100%;
    max-width: var(--content-max-width);
    padding: 3rem 2rem 5rem;
    margin: 0 auto;
}

/* Table of Contents Column */
.table-of-contents {
    grid-area: toc;
    position: sticky;
    top: calc(var(--header-height) + 2rem);
    height: calc(100vh - var(--header-height) - 4rem);
    overflow-y: auto;
    padding-right: 1rem;
    padding-left: 1.5rem;
    /* Add breathing room from content */
    border-left: 1px solid var(--border-color);
    display: block;
    background-color: transparent;
    /* Seamless with body bg */
    width: auto;
    right: auto;
}

/* Responsive: Laptop/Tablet (Hide TOC column, specific breakpoints) */
@media (max-width: 1200px) {
    .layout-container {
        grid-template-columns: var(--sidebar-width) 1fr;
        grid-template-areas: "sidebar content";
    }

    .table-of-contents {
        display: none;
        /* Hide TOC on smaller screens */
        /* Future enhancement: Move TOC inside content or toggle */
    }
}

/* Responsive: Mobile (Single column) */
@media (max-width: 900px) {
    .layout-container {
        display: block;
        /* Fallback to block for simple stacking */
    }

    .sidebar {
        position: fixed;
        left: 0;
        top: var(--header-height);
        bottom: 0;
        width: 280px;
        transform: translateX(-100%);
        box-shadow: none;
        height: calc(100vh - var(--header-height));
    }

    .sidebar.open {
        transform: translateX(0);
        box-shadow: 100vw 0 0 rgba(0, 0, 0, 0.5);
        /* Backdrop */
    }

    .mobile-menu-toggle {
        display: block;
    }

    .main-content-wrapper {
        margin-left: 0;
        width: 100%;
    }

    .main-content {
        padding: 2rem 1.25rem;
        max-width: 100%;
    }

    .comparison-table {
        min-width: 600px;
        /* Force scroll on mobile */
    }
}

/* Animation */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.main-content {
    animation: fadeIn 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

/* =========================================
   Educational Components & Visuals
   ========================================= */

/* Comparison Tables */
.comparison-table-wrapper {
    overflow-x: auto;
    margin: 2rem 0;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--bg-surface);
}

.comparison-table th,
.comparison-table td {
    padding: 1.25rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.comparison-table th {
    background-color: var(--bg-body);
    font-weight: 700;
    color: var(--color-primary);
    border-bottom: 2px solid var(--color-primary-light);
}

.comparison-table tr:hover td {
    background-color: var(--bg-body);
}

/* Quiz Engine */
.quiz-container {
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2rem;
    margin: 3rem 0;
    box-shadow: var(--shadow-md);
}

.quiz-header {
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.quiz-header h3 {
    margin: 0;
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.quiz-question {
    margin-bottom: 2rem;
}

.question-text {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.quiz-option {
    display: flex;
    align-items: center;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.2s ease;
    background-color: var(--bg-surface);
}

.quiz-option:hover {
    border-color: var(--color-primary-light);
    background-color: var(--bg-body);
}

.quiz-option.selected {
    border-color: var(--color-primary);
    background-color: var(--color-primary-transparent);
}

.quiz-option.correct {
    border-color: var(--success-border);
    background-color: var(--success-bg);
}

.quiz-option.incorrect {
    border-color: var(--danger-border);
    background-color: var(--danger-bg);
}

.quiz-option input[type="radio"] {
    margin-right: 1rem;
    accent-color: var(--color-primary);
}

.quiz-feedback {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: var(--radius-sm);
    display: none;
    /* Hidden by default */
    font-size: 0.95rem;
}

.quiz-feedback.correct {
    display: block;
    background-color: var(--success-bg);
    color: var(--success-text);
    border-left: 4px solid var(--success-border);
}

.quiz-feedback.incorrect {
    display: block;
    background-color: var(--danger-bg);
    color: var(--danger-text);
    border-left: 4px solid var(--danger-border);
}

.check-answer-btn {
    margin-top: 1rem;
    background-color: var(--color-primary);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

.check-answer-btn:hover {
    background-color: var(--color-primary-dark);
}

.check-answer-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

/* Pedagogical Markers */
.takeaway-box {
    background-color: var(--success-bg);
    border: 1px solid var(--success-border);
    border-radius: var(--radius-md);
    padding: 1.5rem;
    margin: 2rem 0;
}

.takeaway-box h3 {
    color: var(--success-text);
    margin-top: 0;
}

.pitfall-box {
    background-color: var(--danger-bg);
    border: 2px dashed var(--danger-border);
    border-radius: var(--radius-md);
    padding: 1.5rem;
    margin: 2rem 0;
}

.pitfall-box h3 {
    color: var(--danger-text);
    margin-top: 0;
}

.concept-graphic {
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 3rem;
    margin: 2rem 0;
}

/* Enhanced Code Copy Label */
.code-copy-btn.copied {
    background-color: var(--success-border);
    color: white;
}

/* =========================================
   Interactive Tools (Visualizer & Debug)
   ========================================= */

/* Query Visualizer Button */
.explain-btn {
    position: absolute;
    top: 0.5rem;
    right: 5rem;
    /* Left of Copy button */
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    cursor: pointer;
    opacity: 0;
    transition: all 0.2s ease;
    z-index: 10;
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.code-block-wrapper:hover .explain-btn {
    opacity: 1;
}

.explain-btn:hover {
    background-color: var(--color-primary-light);
    color: var(--color-primary);
    border-color: var(--color-primary);
}

/* JSON/Visualizer Modal */
.visualizer-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    z-index: 1100;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 1;
    transition: opacity 0.3s ease;
}

.visualizer-modal.hidden {
    opacity: 0;
    pointer-events: none;
}

.visualizer-content {
    background-color: var(--bg-surface);
    width: 90%;
    max-width: 600px;
    max-height: 80vh;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    border: 1px solid var(--border-color);
}

.visualizer-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--bg-body);
}

.visualizer-header h3 {
    margin: 0;
    color: var(--color-primary);
}

.close-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
}

.visualizer-body {
    padding: 2rem;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

/* Flowchart Steps */
.flow-step {
    background-color: var(--bg-surface);
    border: 2px solid var(--border-color);
    padding: 1rem 1.5rem;
    border-radius: var(--radius-md);
    width: 100%;
    display: flex;
    align-items: center;
    gap: 1rem;
    box-shadow: var(--shadow-sm);
    transition: transform 0.3s ease;
}

.flow-step:hover {
    transform: scale(1.02);
    border-color: var(--color-primary);
}

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

.step-content {
    display: flex;
    flex-direction: column;
}

.step-detail {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-family: 'Fira Code', monospace;
    background-color: var(--bg-body);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    margin-top: 0.2rem;
    display: inline-block;
}

.flow-arrow {
    color: var(--color-primary-light);
    font-size: 1.2rem;
    font-weight: bold;
}

/* Animation */
.animate-in {
    opacity: 0;
    animation: slideDown 0.4s ease forwards;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Debug Challenge Tool */
.debug-challenge {
    background-color: var(--bg-surface);
    border: 2px solid var(--danger-border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    margin: 2rem 0;
    position: relative;
    overflow: hidden;
}

.debug-challenge::before {
    content: "🐞 Debug Challenge";
    position: absolute;
    top: 0;
    left: 0;
    background-color: var(--danger-bg);
    color: var(--danger-text);
    padding: 0.5rem 1rem;
    font-size: 0.8rem;
    font-weight: bold;
    border-bottom-right-radius: var(--radius-md);
}

.debug-header {
    margin-top: 1.5rem;
    margin-bottom: 1rem;
}

.buggy-code {
    border: 2px dashed var(--danger-border) !important;
    opacity: 0.9;
}

.debug-controls {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.hint-btn {
    background-color: var(--bg-body);
    border: 1px solid var(--text-secondary);
    color: var(--text-primary);
    padding: 0.6rem 1.2rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s;
}

.hint-btn:hover {
    background-color: var(--bg-surface);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.reveal-btn {
    background-color: var(--danger-bg);
    border: 1px solid var(--danger-border);
    color: var(--danger-text);
    padding: 0.6rem 1.2rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-weight: 600;
}

.reveal-btn:hover {
    background-color: var(--danger-border);
    color: white;
}

.hint-display {
    margin-top: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.hint-text {
    background-color: #fff9db;
    /* Light yellow */
    color: #856404;
    padding: 0.75rem;
    border-left: 4px solid #ffeeba;
    border-radius: 2px;
    margin: 0;
    font-size: 0.9rem;
}

.solution-code.hidden {
    display: none;
}

.solution-code {
    margin-top: 1.5rem;
    border-color: var(--success-border) !important;
    animation: fadeIn 0.5s ease;
}


/* Top Header */
.top-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 1.5rem;
}

[data-theme="dark"] .top-header {
    background-color: rgba(17, 34, 54, 0.8);
}

.header-title {
    font-weight: 700;
    font-size: 1.125rem;
    color: var(--color-primary);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.theme-toggle {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 0.4rem;
    cursor: pointer;
    transition: all 0.2s;
    color: var(--text-secondary);
}

.theme-toggle:hover {
    background-color: var(--bg-surface);
    border-color: var(--color-primary);
    color: var(--color-primary);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    background: transparent;
    border: none;
    font-size: 1.5rem;
    color: var(--text-primary);
    cursor: pointer;
    margin-right: 1rem;
}

/* Sidebar */
.sidebar-header {
    padding: 1.5rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.sidebar-header h1 {
    font-size: 1.1rem;
    color: #F8FAFC;
    letter-spacing: -0.01em;
    margin: 0;
}

.search-box {
    padding: 1rem 1.5rem;
}

.search-box input {
    width: 100%;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-sm);
    padding: 0.5rem 0.75rem;
    color: #F8FAFC;
    font-family: inherit;
    font-size: 0.875rem;
    transition: all 0.2s;
}

.search-box input:focus {
    outline: none;
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--color-primary);
}

.nav-list {
    list-style: none;
    padding: 0.5rem 0;
    flex: 1;
}

.nav-link {
    display: block;
    padding: 0.75rem 1.5rem;
    color: #94A3B8;
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.2s;
    border-left: 3px solid transparent;
}

.nav-link:hover {
    color: #F8FAFC;
    background-color: rgba(255, 255, 255, 0.02);
}

.nav-link.active {
    color: var(--color-accent);
    background-color: rgba(46, 119, 174, 0.1);
    /* Primary transparent */
    border-left-color: var(--color-accent);
    font-weight: 500;
}



.content-header {
    margin-bottom: 3rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 2rem;
}

.content-header h1 {
    font-size: 2.5rem;
    letter-spacing: -0.02em;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    line-height: 1.2;
}

.subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    font-weight: 400;
}

/* Typography */
h1,
h2,
h3,
h4 {
    color: var(--text-primary);
    margin-top: 2.5rem;
    margin-bottom: 1rem;
    font-weight: 600;
    scroll-margin-top: calc(var(--header-height) + 2rem);
    position: relative;
}

h2 {
    font-size: 1.75rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

h3 {
    font-size: 1.4rem;
}

p {
    margin-bottom: 1.25rem;
    font-size: 1.05rem;
    color: var(--text-primary);
    line-height: 1.75;
}

strong {
    font-weight: 600;
    color: var(--text-primary);
}

ul,
ol {
    margin-bottom: 1.25rem;
    padding-left: 1.5rem;
    color: var(--text-primary);
}

li {
    margin-bottom: 0.5rem;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s;
}

a:hover:not(.btn):not(.nav-link) {
    border-bottom-color: var(--color-primary);
}

/* Code Blocks & Inline Code */
code {
    font-family: 'Fira Code', monospace;
    font-size: 0.9em;
    color: var(--color-primary-dark);
    background-color: var(--bg-code-inline);
    padding: 0.1rem 0.3rem;
    border-radius: 4px;
    border: 1px solid var(--border-color);
}

[data-theme="dark"] code {
    color: var(--color-primary-light);
}

pre {
    background-color: var(--bg-code);
    border-radius: var(--radius-md);
    margin: 1.5rem 0;
    overflow: hidden;
    position: relative;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

pre code {
    display: block;
    padding: 1.5rem;
    color: #E2E8F0;
    /* Always light text in code blocks */
    background-color: transparent;
    border: none;
    font-size: 0.9rem;
    line-height: 1.5;
    overflow-x: auto;
}

.code-block-wrapper {
    position: relative;
}

/* Code Header (Mac-like dots) */
.code-block-wrapper::before {
    content: "";
    display: block;
    height: 12px;
    width: 50px;
    background-image:
        radial-gradient(circle, #EF4444 6px, transparent 7px),
        radial-gradient(circle, #F59E0B 6px, transparent 7px),
        radial-gradient(circle #10B981 6px, transparent 7px);
    background-size: 12px 12px;
    background-position: 0 0, 16px 0, 32px 0;
    background-repeat: no-repeat;
    position: absolute;
    top: 16px;
    left: 16px;
    z-index: 2;
    opacity: 0.6;
}

/* Move copy button */
.code-copy-btn {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    background: rgba(255, 255, 255, 0.1);
    color: #94A3B8;
    border: none;
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all 0.2s;
    font-family: 'Inter', sans-serif;
    z-index: 10;
}

.code-copy-btn:hover {
    background: rgba(255, 255, 255, 0.2);
    color: #F8FAFC;
}

.code-copy-btn.copied {
    background: var(--color-success-bg);
    color: var(--color-success-text);
}

/* Info Boxes */
.info-box {
    margin: 2rem 0;
    padding: 1.5rem;
    border-radius: var(--radius-md);
    border-left: 4px solid;
    background-color: var(--bg-surface);
    box-shadow: var(--shadow-sm);
    position: relative;
}

.info-box h3 {
    margin-top: 0;
    font-size: 1.1rem;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.info-box.info {
    background-color: var(--info-bg);
    border-color: var(--info-border);
    color: var(--info-text);
}

.info-box.warning {
    background-color: var(--warning-bg);
    border-color: var(--warning-border);
    color: var(--warning-text);
}

.info-box.danger {
    background-color: var(--danger-bg);
    border-color: var(--danger-border);
    color: var(--danger-text);
}

.info-box.success {
    background-color: var(--success-bg);
    border-color: var(--success-border);
    color: var(--success-text);
}

/* Tables */
table {
    width: 100%;
    margin: 2rem 0;
    border-collapse: separate;
    border-spacing: 0;
    background-color: var(--bg-surface);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

th,
td {
    padding: 1rem 1.5rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background-color: var(--bg-body);
    font-weight: 600;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
}

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

tr:hover td {
    background-color: var(--bg-body);
}

/* Exercises */
.exercise {
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 2rem;
    margin: 3rem 0;
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
}

.exercise::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background-color: var(--color-primary);
}

.exercise h3 {
    margin-top: 0;
    color: var(--color-primary);
}

.solution-toggle {
    background-color: var(--bg-body);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-weight: 500;
    font-size: 0.9rem;
    transition: all 0.2s;
    margin-top: 1rem;
}

.solution-toggle:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
    background-color: var(--bg-surface);
}

.solution-content {
    display: none;
    margin-top: 1.5rem;
    padding: 1.5rem;
    background-color: var(--bg-code-inline);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
}

.solution-content.show {
    display: block;
    animation: fadeIn 0.3s ease-out;
}

/* Table of Contents */
.table-of-contents {
    position: fixed;
    top: calc(var(--header-height) + 2rem);
    right: max(1rem, calc((100vw - var(--content-max-width) - var(--sidebar-width)) / 2 - var(--toc-width)));
    width: var(--toc-width);
    max-height: calc(100vh - 8rem);
    overflow-y: auto;
    padding-left: 1.5rem;
    border-left: 1px solid var(--border-color);
    display: none;
    /* Hidden on small screens */
}

@media (min-width: 1200px) {
    .table-of-contents {
        display: block;
    }
}

.toc-title {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    font-weight: 600;
    color: var(--text-tertiary);
    margin-bottom: 1rem;
}

.toc-link {
    display: block;
    padding: 0.25rem 0;
    color: var(--text-secondary);
    font-size: 0.875rem;
    border: none;
    transition: all 0.2s;
}

.toc-link:hover {
    color: var(--color-primary);
}

.toc-link.active {
    color: var(--color-primary);
    font-weight: 500;
    transform: translateX(4px);
}

.toc-item {
    list-style: none;
}

.toc-item.level-3 {
    padding-left: 1rem;
}

.toc-item.level-4 {
    padding-left: 2rem;
}

/* Diagrams */
.diagram {
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 2rem;
    margin: 2rem 0;
    text-align: center;
    box-shadow: var(--shadow-md);
    overflow-x: auto;
}

/* Theme-adaptive SVG Styles */
.diagram svg {
    max-width: 100%;
    height: auto;
}

.diagram svg rect {
    fill: var(--bg-surface);
    /* Override inline fill */
    stroke: var(--color-primary);
    /* Override inline stroke */
    stroke-width: 2px;
    rx: 4px;
    /* Rounded corners */
    filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.05));
}

.diagram svg text {
    fill: var(--text-primary);
    font-family: 'Inter', sans-serif;
    font-weight: 500;
}

.diagram svg line,
.diagram svg polyline {
    stroke: var(--text-secondary);
    stroke-width: 2px;
}

.diagram svg polygon {
    fill: var(--text-secondary);
    stroke: none;
}

[data-theme="dark"] .diagram svg text {
    fill: var(--text-primary);
}

/* Course Card (Index) */
.lecture-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.lecture-card {
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 2rem;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
}

.lecture-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary-light);
}

.lecture-number {
    font-size: 3rem;
    font-weight: 700;
    color: rgba(46, 119, 174, 0.1);
    /* Very subtle primary */
    line-height: 1;
    margin-bottom: -1rem;
    z-index: 0;
}

.lecture-card h3 {
    margin-top: 1rem;
    z-index: 1;
}

.lecture-link {
    margin-top: auto;
    display: inline-flex;
    align-items: center;
    font-weight: 600;
    color: var(--color-primary);
}

.btn {
    display: inline-block;
    background-color: var(--color-primary);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    font-weight: 500;
    transition: all 0.2s;
    border: none;
    cursor: pointer;
}

.btn:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
    color: white;
}

/* Mobile Responsiveness */
@media (max-width: 900px) {
    :root {
        --sidebar-width: 0px;
    }

    .sidebar {
        width: 280px;
        transform: translateX(-100%);
    }

    .sidebar.open {
        transform: translateX(0);
        box-shadow: 100vw 0 0 rgba(0, 0, 0, 0.5);
        /* Proper backdrop simulation */
    }

    .mobile-menu-toggle {
        display: block;
    }

    .main-content-wrapper {
        margin-left: 0;
        width: 100%;
    }

    .main-content {
        padding: 2rem 1rem;
    }

    .table-of-contents {
        display: none;
    }
}

/* =========================================
   Contact Card
   ========================================= */
.contact-card {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.25rem;
    margin: 2rem 0;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    text-decoration: none;
    transition: all 0.2s ease;
    box-shadow: var(--shadow-sm);
}

.contact-link:hover {
    background-color: var(--color-primary-transparent);
    border-color: var(--color-primary-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.contact-icon {
    font-size: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    background-color: var(--bg-body);
    border-radius: var(--radius-sm);
}

.contact-details {
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.contact-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.contact-value {
    font-size: 1rem;
    color: var(--text-primary);
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}


/* Explicit TOC List Reset */
.toc-list {
    margin: 0;
    padding: 0;
}