:root {
    --bg: #f6f8fb;
    --card: #ffffff;
    --text: #172033;
    --muted: #667085;
    --line: #e5eaf2;
    --brand: #1f4f8f;
    --brand-soft: #eaf2ff;
    --accent: #f08a4b;
    --radius: 22px;
    --shadow: 0 18px 45px rgba(31, 79, 143, .10);
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
}
a { color: inherit; text-decoration: none; }
a:hover { color: var(--brand); }
img { max-width: 100%; display: block; }
button, input { font: inherit; }
.site-header {
    position: sticky;
    top: 0;
    z-index: 20;
    background: rgba(246,248,251,.94);
    backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--line);
}
.topbar, .main-nav, .search-wrap, main, .site-footer { width: min(1180px, calc(100% - 32px)); margin: auto; }
.topbar { display: flex; align-items: center; justify-content: space-between; gap: 18px; padding: 18px 0 12px; }
.brand-logo { display: inline-flex; align-items: center; gap: 12px; min-width: max-content; }
.logo-mark { display: grid; place-items: center; width: 54px; height: 54px; border-radius: 18px; color: #fff; background: linear-gradient(135deg, var(--brand), #4c78bd); font-weight: 900; letter-spacing: -1px; }
.brand-logo small { display: block; color: var(--muted); font-size: 12px; margin-top: 2px; }
.domain-pill { background: var(--brand-soft); color: var(--brand); border: 1px solid #d8e7ff; padding: 8px 12px; border-radius: 999px; font-size: 14px; }
.main-nav { display: flex; gap: 10px; overflow-x: auto; padding: 0 0 12px; }
.main-nav a { flex: 0 0 auto; padding: 9px 14px; border-radius: 999px; color: #3d4a5f; background: #fff; border: 1px solid var(--line); }
.main-nav a.is-active, .main-nav a:hover { background: var(--brand); color: #fff; border-color: var(--brand); }
.search-wrap { padding: 0 0 16px; }
.search-wrap label { display: block; font-weight: 700; margin-bottom: 8px; }
.search-box { display: flex; gap: 10px; }
.search-box input { flex: 1; border: 1px solid var(--line); border-radius: 16px; padding: 13px 16px; background: #fff; outline: none; }
.search-box input:focus { border-color: var(--brand); box-shadow: 0 0 0 3px rgba(31,79,143,.10); }
.search-box button, .primary-btn, .secondary-btn, .actions button, .share-panel button { border: 0; cursor: pointer; border-radius: 16px; padding: 12px 18px; font-weight: 700; }
.search-box button, .primary-btn { background: var(--brand); color: #fff; }
.secondary-btn { background: #fff; color: var(--brand); border: 1px solid #cfe0f8; }
.search-hint { margin: 8px 0 0; color: var(--muted); font-size: 14px; }
.section-block { margin: 28px auto; padding: 34px; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.hero { display: grid; grid-template-columns: 1.08fr .92fr; gap: 32px; align-items: center; margin-top: 28px; }
.eyebrow { margin: 0 0 8px; color: var(--brand); font-weight: 800; letter-spacing: .02em; }
h1, h2, h3 { line-height: 1.25; margin: 0 0 12px; }
h1 { font-size: clamp(32px, 6vw, 54px); letter-spacing: -.03em; }
h2 { font-size: clamp(24px, 3vw, 34px); }
h3 { font-size: 20px; }
.hero-copy p { font-size: 18px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin: 22px 0; }
.stats-row { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; }
.stats-row span { background: var(--brand-soft); border: 1px solid #d8e7ff; padding: 14px; border-radius: 18px; color: var(--muted); }
.stats-row strong { display: block; color: var(--brand); font-size: 22px; }
.hero-media { margin: 0; position: relative; }
.hero-media img { border-radius: 28px; border: 1px solid var(--line); box-shadow: var(--shadow); }
.hero-media figcaption, .image-description { font-size: 13px; color: var(--muted); margin-top: 8px; }
.compact-section { box-shadow: none; }
.section-heading { max-width: 820px; margin: 0 auto 22px; text-align: center; }
.section-heading.align-left { text-align: left; margin-left: 0; }
.focus-list { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.focus-list a { background: var(--brand-soft); border: 1px solid #d8e7ff; border-radius: 18px; padding: 18px; font-weight: 800; color: var(--brand); }
.video-grid, .module-grid, .category-grid, .author-grid, .comment-grid { display: grid; gap: 18px; }
.video-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.module-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.category-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.author-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.comment-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.video-card, .module-card, .category-card, .author-card, .comment-card, .audit-panel, .article-page { border: 1px solid var(--line); border-radius: 20px; background: #fff; padding: 18px; }
.video-card figure { margin: 0 0 14px; position: relative; overflow: hidden; border-radius: 18px; background: #edf4ff; }
.video-card img { aspect-ratio: 16 / 10; width: 100%; object-fit: cover; transition: transform .25s ease; }
.video-card:hover img { transform: scale(1.03); }
.video-shell { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; opacity: 0; pointer-events: none; }
.play-button { position: absolute; left: 50%; top: 50%; transform: translate(-50%,-50%) scale(.9); width: 64px; height: 64px; border-radius: 999px; background: rgba(31,79,143,.92); color: #fff; opacity: 0; transition: .2s; box-shadow: 0 10px 30px rgba(0,0,0,.25); }
.video-card:hover .play-button, .video-card.is-hover .play-button { opacity: 1; transform: translate(-50%,-50%) scale(1); }
.video-body h3 a { color: var(--text); }
.video-body h3 a:hover { color: var(--brand); }
.meta-grid { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0; }
.meta-grid span { background: #f5f7fb; border: 1px solid var(--line); color: #526071; padding: 5px 9px; border-radius: 999px; font-size: 13px; }
.eeat { color: var(--muted); font-size: 13px; }
.tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0; }
.tags span { background: #fff6ee; color: #9b4f20; border: 1px solid #ffdfc4; padding: 5px 10px; border-radius: 999px; font-size: 13px; }
.actions { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; border-top: 1px solid var(--line); padding-top: 12px; }
.actions button { padding: 8px 10px; background: #eef4ff; color: var(--brand); }
.actions a, .text-link, .more-link { color: var(--brand); font-weight: 800; }
.module-card, .category-card { display: flex; flex-direction: column; justify-content: space-between; min-height: 230px; }
.module-card ul { padding-left: 20px; color: #4a5568; }
.card-footer { display: flex; justify-content: space-between; gap: 12px; align-items: center; color: var(--muted); border-top: 1px solid var(--line); padding-top: 12px; margin-top: 12px; }
.category-card a { margin-top: 12px; color: var(--brand); font-weight: 800; }
.split-section { display: grid; grid-template-columns: 1fr 320px; gap: 22px; align-items: start; }
.audit-panel { position: sticky; top: 190px; background: linear-gradient(180deg, #fff, #f5f9ff); }
.audit-panel ul { padding-left: 20px; }
.author-card { display: grid; grid-template-columns: 96px 1fr; gap: 14px; align-items: center; }
.author-card img { width: 96px; height: 96px; border-radius: 24px; object-fit: cover; border: 1px solid var(--line); }
.comment-card time { color: var(--muted); font-size: 13px; }
.faq-list { display: grid; gap: 12px; max-width: 900px; margin: auto; }
details { background: #f8fbff; border: 1px solid var(--line); padding: 16px 18px; border-radius: 18px; }
summary { cursor: pointer; font-weight: 800; }
.contact-strip { display: flex; align-items: center; justify-content: space-between; gap: 20px; background: linear-gradient(135deg, var(--brand), #416ead); color: #fff; }
.contact-strip .eyebrow, .contact-strip p { color: #fff; }
.contact-strip .primary-btn { background: #fff; color: var(--brand); }
.page-hero { background: linear-gradient(135deg, #fff, #edf5ff); }
.breadcrumbs { width: min(1180px, calc(100% - 32px)); margin: 20px auto -8px; color: var(--muted); font-size: 14px; }
.breadcrumbs a { color: var(--brand); font-weight: 700; }
.article-header { max-width: 860px; }
.article-content { max-width: 860px; margin-top: 22px; }
.site-footer { padding: 36px 0; color: #d7e5ff; }
.site-footer { width: 100%; background: #172033; margin-top: 36px; }
.footer-grid, .footer-note { width: min(1180px, calc(100% - 32px)); margin: auto; }
.footer-grid { display: grid; grid-template-columns: 1fr 1.2fr 1fr; gap: 24px; padding-top: 36px; }
.footer-logo .logo-mark { background: #fff; color: var(--brand); }
.site-footer h2, .site-footer strong { color: #fff; }
.share-panel { display: flex; flex-wrap: wrap; gap: 8px; align-content: start; }
.share-panel h2 { width: 100%; }
.share-panel button { background: rgba(255,255,255,.12); color: #fff; border: 1px solid rgba(255,255,255,.22); padding: 9px 12px; }
.footer-note { border-top: 1px solid rgba(255,255,255,.14); margin-top: 28px; padding: 20px 0 34px; color: #b8c7df; }
@media (max-width: 980px) {
    .hero, .split-section, .footer-grid { grid-template-columns: 1fr; }
    .video-grid, .module-grid, .comment-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .category-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .audit-panel { position: static; }
}
@media (max-width: 640px) {
    .topbar { align-items: flex-start; flex-direction: column; }
    .search-box, .contact-strip { flex-direction: column; align-items: stretch; }
    .section-block { padding: 22px; }
    .video-grid, .module-grid, .category-grid, .author-grid, .comment-grid, .focus-list, .stats-row { grid-template-columns: 1fr; }
    h1 { font-size: 34px; }
}