/* NBA Analytics Textbook - Clean Professional Theme */

:root {
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
    --font-serif: 'Georgia', 'Times New Roman', serif;

    /* Primary palette */
    --blue-600: #2563eb;
    --blue-700: #1d4ed8;
    --blue-50: #eff6ff;

    /* Neutrals */
    --slate-50: #f8fafc;
    --slate-100: #f1f5f9;
    --slate-200: #e2e8f0;
    --slate-300: #cbd5e1;
    --slate-400: #94a3b8;
    --slate-500: #64748b;
    --slate-600: #475569;
    --slate-700: #334155;
    --slate-800: #1e293b;
    --slate-900: #0f172a;

    --white: #ffffff;
    --green-600: #16a34a;
    --amber-500: #f59e0b;
    --red-600: #dc2626;
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.75;
    color: var(--slate-700);
    background: var(--white);
    margin: 0;
    -webkit-font-smoothing: antialiased;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    color: var(--slate-900);
    font-weight: 700;
    line-height: 1.3;
    margin: 0 0 1rem;
}

h1 { font-size: 2.5rem; letter-spacing: -0.025em; }
h2 { font-size: 1.875rem; letter-spacing: -0.025em; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }

p {
    margin: 0 0 1.5rem;
    color: var(--slate-600);
}

a {
    color: var(--blue-600);
    text-decoration: none;
}

a:hover {
    color: var(--blue-700);
    text-decoration: underline;
}

/* ========================================
   NAVBAR
   ======================================== */
.navbar {
    background: var(--white);
    border-bottom: 1px solid var(--slate-200);
    padding: 0.875rem 0;
}

.navbar-brand {
    font-weight: 700;
    font-size: 1.125rem;
    color: var(--slate-900) !important;
}

.navbar-brand:hover {
    color: var(--blue-600) !important;
    text-decoration: none;
}

.navbar .nav-link {
    color: var(--slate-600) !important;
    font-weight: 500;
    font-size: 0.9375rem;
    padding: 0.5rem 0.875rem !important;
}

.navbar .nav-link:hover,
.navbar .nav-link.active {
    color: var(--blue-600) !important;
}

.navbar .dropdown-menu {
    border: 1px solid var(--slate-200);
    border-radius: 0.5rem;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1);
    padding: 0.5rem;
}

.navbar .dropdown-item {
    font-size: 0.9375rem;
    padding: 0.5rem 0.75rem;
    border-radius: 0.375rem;
    color: var(--slate-700);
}

.navbar .dropdown-item:hover {
    background: var(--slate-100);
    color: var(--blue-600);
}

.navbar .form-control {
    border: 1px solid var(--slate-300);
    font-size: 0.875rem;
    padding: 0.5rem 0.75rem;
}

.navbar .form-control:focus {
    border-color: var(--blue-600);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* ========================================
   HERO
   ======================================== */
.hero-section {
    background: var(--slate-50);
    padding: 5rem 0;
    border-bottom: 1px solid var(--slate-200);
}

.hero-section h1 {
    font-size: 3.25rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    line-height: 1.1;
    margin-bottom: 1.5rem;
}

.hero-section .lead {
    font-size: 1.25rem;
    line-height: 1.8;
    color: var(--slate-600);
    max-width: 540px;
}

.hero-section .badge {
    background: var(--blue-600) !important;
    font-weight: 600;
    font-size: 0.75rem;
    padding: 0.5rem 0.875rem;
    letter-spacing: 0.02em;
}

/* Code preview */
.code-preview {
    background: var(--slate-900);
    border-radius: 0.75rem;
    overflow: hidden;
    box-shadow: 0 25px 50px -12px rgba(0,0,0,0.25);
}

.code-preview .code-header {
    background: var(--slate-800);
    padding: 0.75rem 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.code-preview .code-header::before {
    content: '';
    display: flex;
    gap: 0.375rem;
}

.code-preview pre {
    margin: 0;
    padding: 1.25rem;
    overflow-x: auto;
}

.code-preview code {
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    line-height: 1.7;
}

/* ========================================
   BUTTONS
   ======================================== */
.btn {
    font-weight: 600;
    font-size: 0.9375rem;
    padding: 0.625rem 1.25rem;
    border-radius: 0.5rem;
    transition: all 0.15s;
}

.btn-lg {
    padding: 0.875rem 1.75rem;
    font-size: 1rem;
}

.btn-primary {
    background: var(--blue-600);
    border-color: var(--blue-600);
}

.btn-primary:hover {
    background: var(--blue-700);
    border-color: var(--blue-700);
}

.btn-outline-primary {
    color: var(--blue-600);
    border: 2px solid var(--blue-600);
    background: transparent;
}

.btn-outline-primary:hover {
    background: var(--blue-600);
    color: var(--white);
}

.btn-outline-secondary {
    color: var(--slate-600);
    border: 1px solid var(--slate-300);
}

.btn-outline-secondary:hover {
    background: var(--slate-100);
    color: var(--slate-800);
    border-color: var(--slate-400);
}

/* ========================================
   CARDS
   ======================================== */
.card {
    background: var(--white);
    border: 1px solid var(--slate-200);
    border-radius: 0.75rem;
    transition: all 0.2s;
}

.card:hover {
    border-color: var(--slate-300);
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.card-body {
    padding: 1.5rem;
}

.card-title {
    font-weight: 600;
    color: var(--slate-900);
    margin-bottom: 0.5rem;
}

.card-text {
    color: var(--slate-600);
    line-height: 1.6;
}

/* Chapter cards */
.chapter-card:hover {
    border-color: var(--blue-600);
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.08);
}

.chapter-card:hover .card-title {
    color: var(--blue-600);
}

/* ========================================
   SECTIONS
   ======================================== */
section {
    padding: 5rem 0;
}

section.bg-light {
    background: var(--slate-50);
}

.section-header {
    text-align: center;
    max-width: 640px;
    margin: 0 auto 3rem;
}

.section-header h2 {
    margin-bottom: 0.75rem;
}

.section-header p {
    font-size: 1.125rem;
    color: var(--slate-500);
    margin: 0;
}

/* Partners bar */
.partners-bar {
    background: var(--slate-50);
    border-top: 1px solid var(--slate-200);
    border-bottom: 1px solid var(--slate-200);
    padding: 1.25rem 0;
}

.partners-bar span {
    color: var(--slate-400);
    font-weight: 600;
    font-size: 0.8125rem;
    letter-spacing: 0.05em;
}

/* Feature icons */
.feature-icon {
    width: 3rem;
    height: 3rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: var(--blue-50);
    color: var(--blue-600);
    border-radius: 0.625rem;
    font-size: 1.25rem;
}

/* ========================================
   BADGES
   ======================================== */
.badge {
    font-weight: 600;
    font-size: 0.75rem;
    padding: 0.375rem 0.625rem;
    border-radius: 0.375rem;
}

.badge-beginner,
.badge.bg-success {
    background: #dcfce7 !important;
    color: #166534 !important;
}

.badge-intermediate,
.badge.bg-warning {
    background: #fef3c7 !important;
    color: #92400e !important;
}

.badge-advanced,
.badge.bg-danger {
    background: #fee2e2 !important;
    color: #991b1b !important;
}

.badge.bg-primary {
    background: var(--blue-600) !important;
}

.badge.bg-secondary {
    background: var(--slate-500) !important;
}

/* ========================================
   CHAPTER CONTENT
   ======================================== */
.chapter-content {
    font-size: 1.0625rem;
    line-height: 1.85;
    color: var(--slate-700);
}

.chapter-content h2 {
    margin-top: 3rem;
    margin-bottom: 1.25rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--slate-200);
}

.chapter-content h2:first-child {
    margin-top: 0;
}

.chapter-content h3 {
    margin-top: 2.5rem;
    margin-bottom: 1rem;
}

.chapter-content p {
    margin-bottom: 1.5rem;
    color: var(--slate-700);
}

.chapter-content ul,
.chapter-content ol {
    margin-bottom: 1.5rem;
    padding-left: 1.25rem;
}

.chapter-content li {
    margin-bottom: 0.5rem;
}

.chapter-content blockquote {
    border-left: 3px solid var(--blue-600);
    margin: 2rem 0;
    padding: 1rem 1.5rem;
    background: var(--slate-50);
    border-radius: 0 0.5rem 0.5rem 0;
}

.chapter-content blockquote p {
    margin: 0;
    color: var(--slate-600);
    font-style: italic;
}

/* Inline code */
.chapter-content code {
    background: var(--slate-100);
    color: var(--red-600);
    padding: 0.125rem 0.375rem;
    border-radius: 0.25rem;
    font-family: var(--font-mono);
    font-size: 0.875em;
}

/* Code blocks */
.chapter-content pre {
    background: var(--slate-900);
    border-radius: 0.5rem;
    padding: 1.25rem;
    margin: 1.5rem 0;
    overflow-x: auto;
}

.chapter-content pre code {
    background: none;
    color: inherit;
    padding: 0;
    font-size: 0.875rem;
    line-height: 1.6;
}

/* Code toggle */
.code-toggle .btn {
    border-radius: 0.5rem 0.5rem 0 0;
    border: 1px solid var(--slate-300);
    border-bottom: none;
    background: var(--slate-100);
    color: var(--slate-600);
    font-size: 0.8125rem;
    font-weight: 600;
    padding: 0.5rem 1rem;
}

.code-toggle .btn.active {
    background: var(--slate-900);
    color: var(--white);
    border-color: var(--slate-900);
}

.code-block pre {
    border-radius: 0 0.5rem 0.5rem 0.5rem;
    margin-top: 0;
}

/* ========================================
   TABLE OF CONTENTS
   ======================================== */
.toc-sidebar {
    position: sticky;
    top: 6rem;
}

.toc-sidebar h6 {
    font-size: 0.6875rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--slate-400);
    margin-bottom: 1rem;
}

.toc-nav .nav-link {
    font-size: 0.875rem;
    color: var(--slate-500);
    padding: 0.375rem 0 0.375rem 1rem;
    border-left: 2px solid transparent;
    margin-left: -2px;
}

.toc-nav .nav-link:hover {
    color: var(--slate-700);
}

.toc-nav .nav-link.active {
    color: var(--blue-600);
    border-left-color: var(--blue-600);
    font-weight: 600;
}

/* ========================================
   GLOSSARY
   ======================================== */
.letter-filter {
    padding: 0.375rem 0.625rem;
    font-weight: 600;
    font-size: 0.8125rem;
}

.letter-filter.active {
    background: var(--blue-600);
    border-color: var(--blue-600);
}

.glossary-term {
    background: var(--white);
    border: 1px solid var(--slate-200);
    border-radius: 0.5rem;
    padding: 1.25rem;
    margin-bottom: 1rem;
}

.glossary-term:hover {
    border-color: var(--blue-600);
}

.glossary-term h5 {
    color: var(--blue-600);
    margin-bottom: 0.5rem;
    font-size: 1.125rem;
}

.glossary-term p {
    margin: 0;
    color: var(--slate-600);
}

/* ========================================
   EXERCISES
   ======================================== */
.exercise-card {
    border-left: 4px solid var(--blue-600);
}

.exercise-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.08);
}

/* ========================================
   RESOURCES
   ======================================== */
.resource-card {
    background: var(--white);
    border: 1px solid var(--slate-200);
    border-radius: 0.5rem;
    padding: 1.25rem;
    margin-bottom: 1rem;
}

.resource-card:hover {
    border-color: var(--blue-600);
}

.resource-card h6 {
    margin-bottom: 0.25rem;
}

.resource-card h6 a {
    color: var(--slate-800);
}

.resource-card h6 a:hover {
    color: var(--blue-600);
}

.resource-card p {
    margin: 0;
    font-size: 0.9375rem;
    color: var(--slate-500);
}

/* ========================================
   FOOTER
   ======================================== */
.footer {
    background: var(--slate-900);
    color: var(--slate-400);
    padding: 4rem 0 2rem;
}

.footer h5,
.footer h6 {
    color: var(--white);
    font-size: 0.9375rem;
    margin-bottom: 1.25rem;
}

.footer p {
    color: var(--slate-400);
    font-size: 0.9375rem;
}

.footer a {
    color: var(--slate-400);
}

.footer a:hover {
    color: var(--white);
    text-decoration: none;
}

.footer ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.footer ul li {
    margin-bottom: 0.625rem;
}

.footer ul li a {
    font-size: 0.9375rem;
}

.footer hr {
    border-color: var(--slate-700);
    margin: 2.5rem 0 1.5rem;
}

.footer .copyright {
    font-size: 0.875rem;
    color: var(--slate-500);
}

.footer-link {
    color: var(--slate-400) !important;
}

.footer-link:hover {
    color: var(--white) !important;
}

/* ========================================
   FORMS
   ======================================== */
.form-control {
    border: 1px solid var(--slate-300);
    border-radius: 0.5rem;
    padding: 0.625rem 0.875rem;
    font-size: 0.9375rem;
}

.form-control:focus {
    border-color: var(--blue-600);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* ========================================
   TABLES
   ======================================== */
.table {
    font-size: 0.9375rem;
}

.table thead th {
    background: var(--slate-50);
    border-bottom: 2px solid var(--slate-200);
    font-weight: 600;
    color: var(--slate-700);
    padding: 0.875rem;
}

.table td {
    padding: 0.875rem;
    border-color: var(--slate-200);
    color: var(--slate-600);
}

/* ========================================
   UTILITIES
   ======================================== */
.text-primary { color: var(--blue-600) !important; }
.text-muted { color: var(--slate-500) !important; }
.bg-light { background: var(--slate-50) !important; }
.border-primary { border-color: var(--blue-600) !important; }

/* Container for main content */
main.container {
    background: var(--white);
    border-radius: 0.75rem;
    padding: 2rem;
    margin-top: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}

/* ========================================
   RESPONSIVE
   ======================================== */
@media (max-width: 991.98px) {
    section {
        padding: 3.5rem 0;
    }

    .hero-section {
        padding: 3rem 0;
    }

    .hero-section h1 {
        font-size: 2.5rem;
    }

    .toc-sidebar {
        display: none;
    }

    main.container {
        padding: 1.5rem;
        border-radius: 0;
        margin-top: 0;
    }
}

@media (max-width: 767.98px) {
    .hero-section h1 {
        font-size: 2rem;
    }

    .hero-section .lead {
        font-size: 1.0625rem;
    }

    .section-header h2 {
        font-size: 1.5rem;
    }

    .card-body {
        padding: 1.25rem;
    }
}

/* ========================================
   PRINT
   ======================================== */
@media print {
    .navbar, .footer, .toc-sidebar {
        display: none !important;
    }

    body {
        font-size: 11pt;
        color: #000;
    }

    .chapter-content pre {
        white-space: pre-wrap;
        border: 1px solid #ccc;
        background: #f5f5f5;
    }

    .card {
        border: 1px solid #ddd;
        box-shadow: none;
    }
}

/* ========================================
   DARK MODE
   ======================================== */
[data-theme="dark"] {
    --bg-body: #0f172a;
    --bg-surface: #1e293b;
    --bg-elevated: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
}

[data-theme="dark"] body {
    background: var(--bg-body);
    color: var(--text-primary);
}

[data-theme="dark"] h1,
[data-theme="dark"] h2,
[data-theme="dark"] h3,
[data-theme="dark"] h4,
[data-theme="dark"] h5,
[data-theme="dark"] h6 {
    color: var(--text-primary);
}

[data-theme="dark"] p,
[data-theme="dark"] .text-muted {
    color: var(--text-secondary) !important;
}

[data-theme="dark"] .navbar {
    background: var(--bg-surface) !important;
    border-bottom-color: var(--border-color);
}

[data-theme="dark"] .navbar-brand,
[data-theme="dark"] .nav-link {
    color: var(--text-primary) !important;
}

[data-theme="dark"] .card {
    background: var(--bg-surface) !important;
    border-color: var(--border-color) !important;
}

[data-theme="dark"] .card-header,
[data-theme="dark"] .card-footer {
    background: var(--bg-elevated) !important;
    border-color: var(--border-color) !important;
}

[data-theme="dark"] main.container {
    background: var(--bg-surface);
}

[data-theme="dark"] .hero-section {
    background: linear-gradient(135deg, var(--bg-surface) 0%, var(--bg-body) 100%);
}

[data-theme="dark"] .footer {
    background: var(--bg-surface);
    border-top-color: var(--border-color);
}

[data-theme="dark"] .btn-outline-primary {
    color: var(--blue-600);
    border-color: var(--blue-600);
}

[data-theme="dark"] .table {
    color: var(--text-primary);
}

[data-theme="dark"] .table td,
[data-theme="dark"] .table th {
    border-color: var(--border-color);
    color: var(--text-secondary);
}

[data-theme="dark"] pre,
[data-theme="dark"] code {
    background: var(--bg-body) !important;
}

[data-theme="dark"] .chapter-content pre {
    background: var(--bg-body) !important;
    border-color: var(--border-color);
}

[data-theme="dark"] .breadcrumb {
    background: transparent;
}

[data-theme="dark"] .breadcrumb-item a {
    color: var(--text-secondary);
}

[data-theme="dark"] .form-control {
    background: var(--bg-elevated);
    border-color: var(--border-color);
    color: var(--text-primary);
}

[data-theme="dark"] .form-control:focus {
    background: var(--bg-elevated);
    border-color: var(--blue-600);
    color: var(--text-primary);
}

[data-theme="dark"] .list-group-item {
    background: var(--bg-surface);
    border-color: var(--border-color);
    color: var(--text-primary);
}

[data-theme="dark"] .accordion-button {
    background: var(--bg-surface);
    color: var(--text-primary);
}

[data-theme="dark"] .accordion-button:not(.collapsed) {
    background: var(--bg-elevated);
}

[data-theme="dark"] .alert {
    background: var(--bg-elevated);
    border-color: var(--border-color);
    color: var(--text-primary);
}

/* Theme toggle button */
.theme-toggle-btn {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 1px solid var(--slate-300);
    color: var(--slate-600);
    cursor: pointer;
    transition: all 0.2s ease;
}

.theme-toggle-btn:hover {
    background: var(--slate-100);
    color: var(--slate-900);
}

[data-theme="dark"] .theme-toggle-btn {
    border-color: var(--border-color);
    color: var(--text-secondary);
}

[data-theme="dark"] .theme-toggle-btn:hover {
    background: var(--bg-elevated);
    color: var(--text-primary);
}

/* Progress tracking styles */
.progress-container {
    background: var(--slate-100);
    border-radius: 0.5rem;
    padding: 1rem;
    margin-bottom: 1rem;
}

[data-theme="dark"] .progress-container {
    background: var(--bg-elevated);
}

.progress-fill {
    height: 8px;
    background: var(--blue-600);
    border-radius: 4px;
    transition: width 0.3s ease;
}

.chapter-complete-badge {
    font-size: 0.875rem;
}

.continue-reading-btn {
    display: none;
}