:root {
  --brand: #14539a;
  --brand-dark: #0d3a6e;
  --brand-light: #e8f1fb;
  --ink: #1f2937;
  --muted: #6b7280;
  --line: #e5e7eb;
  --bg: #ffffff;
  --bg-alt: #f7f9fc;
  --radius: 12px;
  --maxw: 1160px;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
  font-size: 15px;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.92);
  backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; }
.logo-img { height: 34px; }
.logo-text { font-size: 20px; font-weight: 700; color: var(--brand); }
.site-nav { display: flex; gap: 28px; }
.site-nav a { color: var(--muted); font-weight: 500; transition: color .15s; }
.site-nav a:hover, .site-nav a.active { color: var(--brand); }

/* Hero */
.hero { background: linear-gradient(135deg, var(--brand) 0%, var(--brand-dark) 100%); color: #fff; padding: 72px 0 64px; }
.hero-title { font-size: 40px; margin: 0 0 14px; font-weight: 800; letter-spacing: 1px; }
.hero-sub { font-size: 17px; opacity: .9; max-width: 720px; margin: 0 0 28px; }
.hero-actions { display: flex; gap: 14px; }
.btn { display: inline-block; padding: 11px 24px; border-radius: 999px; font-weight: 600; transition: transform .12s, box-shadow .12s; }
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: #fff; color: var(--brand); }
.btn-ghost { border: 1px solid rgba(255,255,255,.6); color: #fff; }

/* Section */
.section { padding: 52px 0; }
.section--alt { background: var(--bg-alt); }
.section-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 24px; }
.section-head h2 { font-size: 24px; margin: 0; }
.more { color: var(--brand); font-weight: 600; }

/* Card grid */
.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
@media (max-width: 880px) { .card-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .card-grid { grid-template-columns: 1fr; } }
.article-card { border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; background: #fff; transition: box-shadow .18s, transform .18s; }
.article-card:hover { box-shadow: 0 10px 28px rgba(20,83,154,.12); transform: translateY(-3px); }
.card-cover { height: 168px; background-size: cover; background-position: center; background-color: var(--brand-light); }
.card-cover--empty { display: flex; align-items: center; justify-content: center; color: var(--brand); font-weight: 600; }
.card-body { padding: 16px 18px 20px; }
.card-tag { display: inline-block; font-size: 12px; color: var(--brand); background: var(--brand-light); padding: 2px 10px; border-radius: 999px; margin-bottom: 10px; }
.card-title { font-size: 17px; margin: 0 0 8px; line-height: 1.45; }
.card-summary { color: var(--muted); margin: 0 0 12px; font-size: 14px; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.card-date { color: #9ca3af; font-size: 13px; }

/* Channels */
.channels { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }
@media (max-width: 560px) { .channels { grid-template-columns: 1fr; } }
.channel { display: block; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 30px; transition: box-shadow .18s, transform .18s; }
.channel:hover { box-shadow: 0 10px 28px rgba(20,83,154,.12); transform: translateY(-3px); }
.channel-num { font-size: 38px; font-weight: 800; color: var(--brand); }
.channel-name { font-size: 19px; font-weight: 700; margin: 4px 0 8px; }
.channel-desc { color: var(--muted); font-size: 14px; }

/* Article detail */
.article-inner { max-width: 820px; padding-top: 32px; padding-bottom: 56px; }
.back { color: var(--brand); font-weight: 600; display: inline-block; margin-bottom: 18px; }
.article-meta { color: var(--muted); font-size: 14px; display: flex; gap: 14px; align-items: center; margin-bottom: 12px; flex-wrap: wrap; }
.article-meta .tag { color: var(--brand); background: var(--brand-light); padding: 2px 10px; border-radius: 999px; font-weight: 600; }
.article-title { font-size: 30px; line-height: 1.35; margin: 0 0 22px; }
.article-cover { height: 320px; background-size: cover; background-position: center; border-radius: var(--radius); margin-bottom: 26px; background-color: var(--brand-light); }
.article-content { font-size: 16px; }
.article-content img { border-radius: 8px; margin: 16px 0; }
.article-content p { margin: 0 0 16px; }

/* About */
.about h2 { font-size: 26px; margin: 0 0 14px; }
.about h3 { font-size: 20px; margin: 34px 0 16px; }
.about-contact { background: var(--bg-alt); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px 22px; margin: 18px 0 8px; color: var(--muted); }
.about-contact div { margin: 4px 0; }

.empty { color: var(--muted); padding: 40px; text-align: center; border: 1px dashed var(--line); border-radius: var(--radius); }

/* Footer */
.site-footer { background: var(--brand-dark); color: #cbd5e1; padding: 36px 0; margin-top: 40px; }
.footer-inner { display: flex; flex-direction: column; gap: 8px; align-items: center; text-align: center; }
.footer-brand { font-size: 18px; font-weight: 700; color: #fff; }
.footer-meta { display: flex; gap: 18px; flex-wrap: wrap; justify-content: center; font-size: 13px; }
.footer-copy { font-size: 12px; color: #93a4bd; }

/* 首页栏目筛选 tabs */
.filter-tabs { display: flex; gap: 10px; margin: 0 0 20px; flex-wrap: wrap; }
.filter-tab {
  border: 1px solid var(--line); background: #fff; color: var(--muted);
  padding: 7px 18px; border-radius: 999px; cursor: pointer; font-size: 14px;
  font-weight: 500; transition: .15s;
}
.filter-tab:hover { border-color: var(--brand); color: var(--brand); }
.filter-tab.active { background: var(--brand); border-color: var(--brand); color: #fff; }

/* 首页关于我们 */
.section--about { background: #fff; }
.about-home { display: grid; grid-template-columns: 1.5fr 1fr; gap: 32px; align-items: stretch; }
.about-home-text h2 { font-size: 26px; margin: 0 0 16px; }
.about-home-text p { color: var(--muted); line-height: 1.9; margin: 0 0 22px; }
.about-home-contact {
  background: var(--bg-alt); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 24px; display: flex; flex-direction: column;
}
.about-home-contact h3 { font-size: 18px; margin: 0 0 14px; }
.about-home-contact div { color: var(--muted); margin-bottom: 8px; font-size: 14px; }
.about-home-contact .btn { margin-top: auto; align-self: flex-start; }
.btn-brand { border: 1px solid var(--brand); color: var(--brand); background: #fff; }
.btn-brand:hover { background: var(--brand); color: #fff; }
@media (max-width: 760px) { .about-home { grid-template-columns: 1fr; } }