/* LLM Course Study Notes - CSS */
:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --bg: #ffffff;
    --bg-alt: #f8fafc;
    --bg-code: #1e293b;
    --text: #1e293b;
    --text-light: #64748b;
    --border: #e2e8f0;
    --accent: #f59e0b;
    --success: #10b981;
    --sidebar-w: 280px;
    --header-h: 60px;
}

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

html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans SC', sans-serif;
    line-height: 1.75;
    color: var(--text);
    background: var(--bg);
}

/* Header */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-h);
    background: #1a1a2e;
    color: #ffffff;
    display: flex;
    align-items: center;
    padding: 0 24px;
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

.header h1 {
    font-size: 1.2rem;
    font-weight: 600;
    color: #ffffff;
}

.header .nav-links {
    margin-left: auto;
    display: flex;
    gap: 8px;
}

.header .nav-links a,
.header .nav-links a:visited,
.header .nav-links a:link {
    color: #ffffff;
    text-decoration: none;
    font-size: 0.85rem;
    padding: 4px 10px;
    border-radius: 4px;
    transition: background 0.2s;
}

.header .nav-links a:hover,
.header .nav-links a.active {
    background: rgba(255,255,255,0.2);
}

/* Sidebar */
.sidebar {
    position: fixed;
    top: var(--header-h);
    left: 0;
    width: var(--sidebar-w);
    height: calc(100vh - var(--header-h));
    background: var(--bg-alt);
    border-right: 1px solid var(--border);
    overflow-y: auto;
    padding: 20px 0;
    z-index: 900;
    transition: transform 0.3s;
}

.sidebar-toggle {
    display: none;
    position: fixed;
    top: calc(var(--header-h) + 10px);
    left: 10px;
    z-index: 950;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 4px;
    padding: 8px 12px;
    cursor: pointer;
    font-size: 1.1rem;
}

.sidebar .toc-title {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-light);
    padding: 0 20px;
    margin-bottom: 8px;
}

.sidebar a,
.sidebar a:visited,
.sidebar a:link {
    display: block;
    padding: 6px 20px;
    color: var(--text);
    text-decoration: none;
    font-size: 0.88rem;
    border-left: 3px solid transparent;
    transition: all 0.2s;
}

.sidebar a:hover {
    background: var(--border);
    border-left-color: var(--primary);
}

.sidebar a.active {
    color: var(--primary);
    border-left-color: var(--primary);
    font-weight: 600;
}

.sidebar a.sub {
    padding-left: 36px;
    font-size: 0.82rem;
    color: var(--text-light);
}

/* Main content */
.main {
    margin-left: var(--sidebar-w);
    margin-top: var(--header-h);
    padding: 40px 60px;
    max-width: 900px;
}

/* Typography */
h1 { font-size: 2rem; margin-bottom: 16px; color: var(--primary-dark); }
h2 { font-size: 1.5rem; margin: 40px 0 16px; padding-bottom: 8px; border-bottom: 2px solid var(--border); }
h3 { font-size: 1.2rem; margin: 28px 0 12px; color: var(--text); }
h4 { font-size: 1rem; margin: 20px 0 8px; }
p { margin-bottom: 12px; }
strong { color: var(--primary-dark); }

/* Lists */
ul, ol { margin: 8px 0 16px 24px; }
li { margin-bottom: 4px; }

/* Tables */
table {
    width: 100%;
    border-collapse: collapse;
    margin: 16px 0;
    font-size: 0.9rem;
}

th {
    background: var(--primary);
    color: white;
    padding: 10px 12px;
    text-align: left;
    font-weight: 600;
}

td {
    padding: 8px 12px;
    border-bottom: 1px solid var(--border);
}

tr:nth-child(even) { background: var(--bg-alt); }
tr:hover { background: #e0e7ff; }

/* Code */
code {
    font-family: 'JetBrains Mono', 'Fira Code', 'Menlo', monospace;
    background: #f1f5f9;
    padding: 2px 6px;
    border-radius: 3px;
    font-size: 0.85em;
}

pre {
    background: var(--bg-code);
    color: #e2e8f0;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 16px 0;
    line-height: 1.5;
}

pre code {
    background: none;
    padding: 0;
    color: inherit;
    font-size: 0.85rem;
}

/* Math */
.math-block {
    overflow-x: auto;
    margin: 16px 0;
    padding: 12px;
    background: #fefce8;
    border-left: 4px solid var(--accent);
    border-radius: 0 6px 6px 0;
}

/* Blockquote */
blockquote {
    border-left: 4px solid var(--primary);
    background: #eff6ff;
    padding: 12px 20px;
    margin: 16px 0;
    border-radius: 0 6px 6px 0;
    font-style: italic;
}

/* Info boxes */
.info-box {
    padding: 16px 20px;
    border-radius: 8px;
    margin: 16px 0;
}

.info-box.key {
    background: #ecfdf5;
    border: 1px solid #a7f3d0;
}

.info-box.warning {
    background: #fffbeb;
    border: 1px solid #fde68a;
}

.info-box.formula {
    background: #fefce8;
    border: 1px solid #fef08a;
}

/* Navigation buttons */
.page-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 60px;
    padding-top: 20px;
    border-top: 2px solid var(--border);
}

.page-nav a,
.page-nav a:visited,
.page-nav a:link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: var(--primary);
    color: white;
    text-decoration: none;
    border-radius: 6px;
    font-size: 0.9rem;
    transition: background 0.2s;
}

.page-nav a:hover { background: var(--primary-dark); }

/* Chapter cards (index page) */
.chapter-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 20px;
    margin: 24px 0;
}

.chapter-card {
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 24px;
    transition: transform 0.2s, box-shadow 0.2s;
}

.chapter-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.chapter-card h3 {
    margin: 0 0 8px;
    color: var(--primary);
}

.chapter-card p {
    font-size: 0.9rem;
    color: var(--text-light);
}

.chapter-card a,
.chapter-card a:visited,
.chapter-card a:link {
    display: inline-block;
    margin-top: 12px;
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.85rem;
}

/* Roadmap */
.roadmap {
    background: var(--bg-alt);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 24px;
    margin: 24px 0;
}

.roadmap pre {
    background: transparent;
    color: var(--text);
    padding: 0;
    margin: 0;
}

/* Badge */
.badge {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-left: 8px;
}

.badge.star { background: #fef3c7; color: #92400e; }

/* Responsive */
@media (max-width: 1024px) {
    .sidebar { transform: translateX(-100%); }
    .sidebar.open { transform: translateX(0); }
    .sidebar-toggle { display: block; }
    .main { margin-left: 0; padding: 30px 20px; }
}

@media (max-width: 600px) {
    .main { padding: 20px 16px; }
    .header h1 { font-size: 1rem; }
    .chapter-grid { grid-template-columns: 1fr; }
    table { font-size: 0.8rem; }
    .page-nav { flex-direction: column; gap: 10px; }
}

/* Scrollbar */
.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

/* Print */
@media print {
    .header, .sidebar, .sidebar-toggle, .page-nav { display: none; }
    .main { margin: 0; padding: 20px; max-width: 100%; }
}