:root {
    /* Light Mode Tokens */
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #64748b;
    --accent-blue: #2563eb;
    --accent-blue-hover: #1d4ed8;
    --accent-green: #16a34a;
    --accent-purple: #9333ea;
    --card-bg: rgba(255, 255, 255, 0.7);
    --card-border: rgba(255, 255, 255, 0.5);
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --glass-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    /* Dark Mode Tokens */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --accent-blue: #3b82f6;
    --accent-blue-hover: #60a5fa;
    --accent-green: #22c55e;
    --accent-purple: #a855f7;
    --card-bg: rgba(30, 41, 59, 0.7);
    --card-border: rgba(255, 255, 255, 0.1);
    --border-color: #334155;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.5);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.5), 0 2px 4px -2px rgb(0 0 0 / 0.5);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5), 0 4px 6px -4px rgb(0 0 0 / 0.5);
    --glass-shadow: 0 4px 30px rgba(0, 0, 0, 0.5);
}

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

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

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

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

/* Layout Container */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

/* Header & Glassmorphism Navigation */
header.main-header {
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
}

.title {
    font-size: clamp(2rem, 5vw, 3rem);
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
}

.subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

.meta-text {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* Controls (Dark Mode Toggle & Search) */
.controls-bar {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.theme-toggle {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--text-primary);
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    cursor: pointer;
    font-weight: 600;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.theme-toggle:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.search-container {
    position: relative;
    width: 100%;
    max-width: 400px;
}

.search-input {
    width: 100%;
    padding: 0.75rem 1.5rem;
    border-radius: 9999px;
    border: 1px solid var(--border-color);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.3);
}

/* Main Content Area */
.glass-panel {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--card-border);
    border-radius: 1.5rem;
    padding: 2rem;
    box-shadow: var(--glass-shadow);
    margin-bottom: 2rem;
}

/* Sections & Grids */
.section-title {
    font-size: 1.5rem;
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 2px solid;
}

.section-blue .section-title { border-color: var(--accent-blue); color: var(--accent-blue); }
.section-green .section-title { border-color: var(--accent-green); color: var(--accent-green); }
.section-purple .section-title { border-color: var(--accent-purple); color: var(--accent-purple); }

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.card-link {
    display: block;
    padding: 1.5rem;
    border-radius: 1rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-weight: 600;
    text-decoration: none;
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
}

.card-link:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.section-blue .card-link:hover { background: rgba(37, 99, 235, 0.05); border-color: var(--accent-blue); color: var(--accent-blue);}
.section-green .card-link:hover { background: rgba(22, 163, 74, 0.05); border-color: var(--accent-green); color: var(--accent-green);}
.section-purple .card-link:hover { background: rgba(147, 51, 234, 0.05); border-color: var(--accent-purple); color: var(--accent-purple);}

/* Tables */
.table-container {
    overflow-x: auto;
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

th {
    background: var(--bg-secondary);
    color: var(--text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.75rem;
    letter-spacing: 0.05em;
    padding: 1rem;
    border-bottom: 2px solid var(--border-color);
    position: sticky;
    top: 0;
    cursor: pointer;
    transition: background 0.2s;
    user-select: none;
}

th:hover {
    background: var(--bg-primary);
}

td {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 0.875rem;
}

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

tr:hover td {
    background: rgba(0, 0, 0, 0.02);
}

[data-theme="dark"] tr:hover td {
    background: rgba(255, 255, 255, 0.02);
}

th.sort-asc::after { content: ' ↑'; color: var(--accent-blue); }
th.sort-desc::after { content: ' ↓'; color: var(--accent-blue); }

.w-9-12 { width: 75%; }
.w-2-12 { width: 16.666%; }
.w-1-12 { width: 8.333%; }

/* Utilities */
.text-center { text-align: center; }
.mb-10 { margin-bottom: 2.5rem; }
.mt-10 { margin-top: 2.5rem; }
.mt-8 { margin-top: 2rem; }

/* Chapter Key List */
.chapter-key {
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    margin-top: 2rem;
}

.chapter-key ul {
    list-style-type: none;
}

.chapter-key li {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
}

.chapter-key li::before {
    content: "•";
    color: var(--accent-blue);
    font-weight: bold;
    display: inline-block; 
    width: 1em;
    margin-left: -1em;
}

.chapter-key b {
    color: var(--text-primary);
    margin-right: 0.5rem;
}

footer {
    text-align: center;
    padding: 2rem 0;
    color: var(--text-muted);
    font-size: 0.875rem;
    border-top: 1px solid var(--border-color);
    margin-top: 3rem;
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.animate-fade-in {
    animation: fadeIn 0.5s ease-out forwards;
}

.hidden {
    display: none !important;
}

/* Back Button */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

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

/* Floating Action Button */
.fab {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: var(--accent-blue);
    color: white;
    width: 3rem;
    height: 3rem;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 1.5rem;
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    transition: all 0.3s ease;
    opacity: 0;
    pointer-events: none;
    transform: scale(0.8);
    border: none;
}

.fab.visible {
    opacity: 1;
    pointer-events: auto;
    transform: scale(1);
}

.fab:hover {
    background: var(--accent-blue-hover);
    transform: scale(1.1);
}