/* AI Glossary — Core Stylesheet */

:root {
    --color-bg: #ffffff;
    --color-surface: #f8fafc;
    --color-border: #e2e8f0;
    --color-text: #1e293b;
    --color-text-muted: #64748b;
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-accent: #7c3aed;
    --radius: 8px;
    --radius-lg: 12px;
    --shadow: 0 1px 3px rgba(0,0,0,0.08);
    --shadow-lg: 0 4px 12px rgba(0,0,0,0.1);
    --max-width: 1120px;
    --nav-height: 60px;
}

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

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--color-primary);
    text-decoration: none;
}
a:hover {
    text-decoration: underline;
}

/* --- Nav --- */
.site-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    height: var(--nav-height);
}
.nav-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    height: 100%;
    gap: 1.5rem;
}
.nav-logo {
    font-weight: 700;
    font-size: 1.15rem;
    color: var(--color-text);
    white-space: nowrap;
}
.nav-logo:hover { text-decoration: none; }
.nav-links {
    display: flex;
    gap: 1rem;
}
.nav-links a {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    font-weight: 500;
}
.nav-links a:hover {
    color: var(--color-text);
    text-decoration: none;
}
.nav-search {
    margin-left: auto;
    flex-shrink: 1;
    min-width: 0;
}
.nav-search input {
    width: 220px;
    padding: 0.4rem 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-size: 0.85rem;
    outline: none;
    transition: border-color 0.2s;
}
.nav-search input:focus {
    border-color: var(--color-primary);
}

/* --- Main --- */
.site-main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 2rem 1.5rem 4rem;
}

/* --- Hero --- */
.hero {
    text-align: center;
    padding: 3rem 0 2.5rem;
}
.hero h1 {
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 0.75rem;
}
.hero-accent {
    color: var(--color-primary);
}
.hero-sub {
    color: var(--color-text-muted);
    font-size: 1.05rem;
    margin-bottom: 1.75rem;
}
.hero-search {
    display: flex;
    max-width: 640px;
    margin: 0 auto;
    gap: 0.5rem;
}
.hero-search input {
    flex: 1;
    padding: 0.85rem 1.25rem;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    outline: none;
    transition: border-color 0.2s;
}
.hero-search input:focus {
    border-color: var(--color-primary);
}
.hero-search button {
    padding: 0.85rem 1.75rem;
    background: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}
.hero-search button:hover {
    background: var(--color-primary-hover);
}

/* --- Sections --- */
.browse-section, .content-section, .search-page, .browse-page, .graph-page {
    margin-bottom: 2.5rem;
}
.browse-section h2, .content-section h2, .term-section h2 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

/* --- Tag Grid --- */
.tag-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}
.tag-chip {
    display: inline-block;
    padding: 0.35rem 0.85rem;
    border: 1px solid var(--color-border);
    border-radius: 999px;
    font-size: 0.85rem;
    color: var(--color-text);
    background: var(--color-surface);
    transition: all 0.15s;
}
.tag-chip:hover {
    background: var(--color-primary);
    color: #fff;
    border-color: var(--color-primary);
    text-decoration: none;
}
.tag-chip-alt {
    border-color: var(--color-accent);
    color: var(--color-accent);
}
.tag-chip-alt:hover {
    background: var(--color-accent);
    color: #fff;
    border-color: var(--color-accent);
}
.tag-chip-sm {
    padding: 0.2rem 0.6rem;
    font-size: 0.75rem;
}

/* --- Difficulty Badge --- */
.difficulty-badge {
    display: inline-block;
    padding: 0.15rem 0.6rem;
    border-radius: 999px;
    font-size: 0.7rem;
    font-weight: 600;
    color: #fff;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    vertical-align: middle;
}

/* --- Term Card --- */
.term-card {
    display: block;
    padding: 1.25rem;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    transition: box-shadow 0.2s, border-color 0.2s;
    color: var(--color-text);
}
.term-card:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
    text-decoration: none;
}
.term-card-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}
.term-card-name {
    font-weight: 600;
    font-size: 1.05rem;
}
.term-card p {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    line-height: 1.5;
}
.term-card-tags {
    margin-top: 0.5rem;
    display: flex;
    gap: 0.35rem;
    flex-wrap: wrap;
}

/* --- Results Grid --- */
.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1rem;
    margin-top: 1rem;
}

/* --- Random Term --- */
.random-term {
    margin-bottom: 2.5rem;
}
.random-term .term-card {
    max-width: 640px;
}

/* --- Term Detail --- */
.term-detail {
    max-width: 780px;
}
.term-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}
.term-header h1 {
    font-size: 2rem;
    font-weight: 700;
}
.term-section {
    margin-bottom: 2rem;
}
.term-short-def {
    font-size: 1.15rem;
    color: var(--color-text);
    line-height: 1.65;
}
.term-long-def {
    font-size: 0.95rem;
    color: var(--color-text-muted);
    line-height: 1.7;
}
.term-list {
    list-style: none;
    padding: 0;
}
.term-list li {
    padding: 0.35rem 0;
    padding-left: 1rem;
    position: relative;
    font-size: 0.95rem;
}
.term-list li::before {
    content: '—';
    position: absolute;
    left: 0;
    color: var(--color-text-muted);
}

/* --- Misconception Card --- */
.misconception-card {
    background: #fef2f2;
    border-left: 3px solid #ef4444;
    padding: 1rem 1.25rem;
    border-radius: var(--radius);
    margin-bottom: 0.75rem;
}
.misconception-wrong {
    font-weight: 600;
    color: #b91c1c;
    margin-bottom: 0.35rem;
    font-size: 0.9rem;
}
.misconception-right {
    color: #166534;
    font-size: 0.9rem;
}

/* --- Related Grid --- */
.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 0.75rem;
}
.related-card {
    display: block;
    padding: 1rem;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    color: var(--color-text);
    transition: border-color 0.2s;
}
.related-card:hover {
    border-color: var(--color-primary);
    text-decoration: none;
}
.related-name {
    font-weight: 600;
    font-size: 0.95rem;
}
.related-type {
    display: inline-block;
    font-size: 0.7rem;
    color: var(--color-text-muted);
    text-transform: uppercase;
    margin-left: 0.35rem;
}
.related-def {
    color: var(--color-text-muted);
    font-size: 0.82rem;
    margin-top: 0.3rem;
    line-height: 1.5;
}

/* --- Search Form --- */
.search-form {
    margin-bottom: 1.5rem;
}
.search-form input[type="search"] {
    width: 100%;
    padding: 0.85rem 1.25rem;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    outline: none;
    margin-bottom: 0.75rem;
}
.search-form input[type="search"]:focus {
    border-color: var(--color-primary);
}
.search-filters {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}
.search-filters select {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-size: 0.85rem;
    background: var(--color-bg);
    cursor: pointer;
}
.search-filters button {
    padding: 0.5rem 1.25rem;
    background: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: var(--radius);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
}
.search-meta {
    color: var(--color-text-muted);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

/* --- Pagination --- */
.pagination {
    display: flex;
    gap: 0.35rem;
    margin-top: 2rem;
    justify-content: center;
}
.page-link {
    display: inline-block;
    padding: 0.4rem 0.8rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-size: 0.85rem;
    color: var(--color-text);
}
.page-link:hover {
    background: var(--color-surface);
    text-decoration: none;
}
.page-link.active {
    background: var(--color-primary);
    color: #fff;
    border-color: var(--color-primary);
}

/* --- Buttons --- */
.btn {
    display: inline-block;
    padding: 0.6rem 1.5rem;
    border-radius: var(--radius);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
}
.btn-outline {
    background: transparent;
    border: 2px solid var(--color-primary);
    color: var(--color-primary);
}
.btn-outline:hover {
    background: var(--color-primary);
    color: #fff;
    text-decoration: none;
}
.btn-sm {
    padding: 0.35rem 0.85rem;
    font-size: 0.8rem;
}

/* --- Graph Page --- */
.graph-controls {
    margin-bottom: 1rem;
}
.graph-toolbar {
    display: flex;
    gap: 1rem;
    align-items: center;
    flex-wrap: wrap;
    margin-top: 0.75rem;
}
.graph-search-form {
    display: flex;
    gap: 0.5rem;
}
.graph-search-form input {
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-size: 0.85rem;
    width: 240px;
}
.graph-search-form button {
    padding: 0.5rem 1rem;
    background: var(--color-primary);
    color: #fff;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-weight: 600;
    font-size: 0.85rem;
}
.graph-options {
    display: flex;
    gap: 0.75rem;
    align-items: center;
}
.graph-options label {
    font-size: 0.85rem;
    color: var(--color-text-muted);
}
.graph-options select {
    padding: 0.3rem 0.5rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-size: 0.85rem;
}
.graph-container {
    width: 100%;
    height: 600px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    background: #fafbfc;
}
.graph-tooltip {
    position: fixed;
    z-index: 200;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1rem;
    box-shadow: var(--shadow-lg);
    max-width: 300px;
    font-size: 0.85rem;
}
.graph-tooltip p {
    color: var(--color-text-muted);
    margin: 0.4rem 0;
}
.graph-legend {
    margin-top: 1rem;
}
.graph-legend h3 {
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}
.legend-items {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}
.legend-item {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.8rem;
    color: var(--color-text-muted);
}
.legend-line {
    width: 20px;
    height: 3px;
    border-radius: 2px;
}
.legend-dashed {
    background: repeating-linear-gradient(90deg, currentColor 0, currentColor 4px, transparent 4px, transparent 8px) !important;
    height: 2px;
}

/* --- About --- */
.about-mission {
    font-size: 1.1rem;
    line-height: 1.7;
    margin-bottom: 2rem;
}
.about-mission p {
    margin-bottom: 0.75rem;
}

/* --- Ads --- */
.ad-banner-top {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0.5rem 1.5rem;
    text-align: center;
}
.ad-inline {
    margin: 2rem 0;
    text-align: center;
}

/* --- Empty State --- */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--color-text-muted);
}

/* --- Footer --- */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding: 2rem 0;
    margin-top: 3rem;
}
.footer-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}
.footer-inner p {
    color: var(--color-text-muted);
    font-size: 0.85rem;
}
.footer-links {
    display: flex;
    gap: 1rem;
}
.footer-links a {
    color: var(--color-text-muted);
    font-size: 0.85rem;
}
.footer-links a:hover {
    color: var(--color-text);
}

/* --- Search Dropdown --- */
.search-dropdown {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    z-index: 200;
    max-height: 400px;
    overflow-y: auto;
}
.search-dropdown-item {
    display: block;
    padding: 0.6rem 0.85rem;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-text);
}
.search-dropdown-item:hover {
    background: var(--color-surface);
    text-decoration: none;
}
.search-dropdown-item strong {
    display: block;
    font-size: 0.9rem;
}
.search-dropdown-item span {
    font-size: 0.78rem;
    color: var(--color-text-muted);
}
.search-dropdown-all {
    display: block;
    padding: 0.6rem 0.85rem;
    text-align: center;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-primary);
}
.search-dropdown-all:hover {
    background: var(--color-surface);
    text-decoration: none;
}

/* --- Responsive --- */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 1.75rem;
    }
    .hero-search {
        flex-direction: column;
    }
    .nav-links {
        display: none;
    }
    .nav-search input {
        width: 160px;
    }
    .results-grid {
        grid-template-columns: 1fr;
    }
    .graph-container {
        height: 400px;
    }
    .graph-toolbar {
        flex-direction: column;
        align-items: flex-start;
    }
    .footer-inner {
        flex-direction: column;
        text-align: center;
    }
    .browse-layout {
        flex-direction: column;
    }
    .alpha-sidebar {
        width: 100%;
        position: static;
    }
    .alpha-nav {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 4px;
        justify-content: center;
    }
}

/* ── Alphabetical Browse Layout ── */
.browse-layout {
    display: flex;
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}
.alpha-sidebar {
    width: 48px;
    flex-shrink: 0;
    position: sticky;
    top: 80px;
    align-self: flex-start;
    height: fit-content;
}
.alpha-nav {
    display: flex;
    flex-direction: column;
    gap: 2px;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 0.5rem 0.25rem;
    box-shadow: var(--shadow);
}
.alpha-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 28px;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--color-primary);
    text-decoration: none;
    border-radius: var(--radius);
    transition: all 0.15s;
}
.alpha-link:hover {
    background: var(--color-primary);
    color: #fff;
}
.alpha-link.active {
    background: var(--color-primary);
    color: #fff;
    font-weight: 700;
}
.alpha-link.disabled {
    color: var(--color-muted);
    opacity: 0.4;
    pointer-events: none;
}
.browse-main {
    flex: 1;
    min-width: 0;
}
.browse-count {
    font-weight: 400;
    color: var(--color-muted);
    font-size: 0.8em;
}

/* A-Z bar on default browse page */
.alpha-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}
.alpha-bar-link {
    display: inline-flex;
    align-items: baseline;
    gap: 0.25rem;
    padding: 0.5rem 0.75rem;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    font-weight: 600;
    font-size: 1rem;
    color: var(--color-primary);
    text-decoration: none;
    transition: all 0.15s;
}
.alpha-bar-link:hover {
    background: var(--color-primary);
    color: #fff;
    border-color: var(--color-primary);
}
.alpha-bar-link small {
    font-size: 0.7rem;
    font-weight: 400;
    opacity: 0.7;
}

/* Dictionary-style term list */
.alpha-term-list {
    display: flex;
    flex-direction: column;
    gap: 1px;
    background: var(--color-border);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
}
.alpha-term-row {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.75rem 1rem;
    background: var(--color-bg);
    text-decoration: none;
    color: var(--color-text);
    transition: background 0.15s;
}
.alpha-term-row:hover {
    background: #f1f5f9;
}
.alpha-term-name {
    font-weight: 600;
    white-space: nowrap;
    min-width: 200px;
    color: var(--color-primary);
}
.alpha-term-def {
    flex: 1;
    font-size: 0.85rem;
    color: var(--color-muted);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.alpha-term-row .difficulty-badge {
    flex-shrink: 0;
}