:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --accent: #7c3aed;
  --bg: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --radius: 14px;
  --shadow: 0 10px 40px rgba(15, 23, 42, 0.08);
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
}
a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }
.container { max-width: 1180px; margin: 0 auto; padding: 0 20px; }
.site-header {
  background: linear-gradient(120deg, var(--primary) 0%, var(--accent) 100%);
  color: #fff;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 4px 24px rgba(37, 99, 235, 0.25);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 68px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: #fff;
  font-weight: 700;
  font-size: 1.2rem;
}
.brand-mark {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: rgba(255,255,255,0.2);
  display: grid;
  place-items: center;
  font-size: 1.1rem;
}
.site-nav ul { display: flex; list-style: none; gap: 8px; }
.site-nav a {
  color: rgba(255,255,255,0.92);
  padding: 8px 16px;
  border-radius: 999px;
  font-weight: 500;
}
.site-nav a:hover,
.site-nav a[aria-current="page"] {
  background: rgba(255,255,255,0.2);
  color: #fff;
}
.hero {
  padding: 72px 0 56px;
  background:
    radial-gradient(circle at 20% 20%, rgba(124,58,237,0.15), transparent 40%),
    radial-gradient(circle at 80% 0%, rgba(37,99,235,0.2), transparent 45%),
    var(--bg);
}
.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 40px;
  align-items: center;
}
.hero h1 {
  font-size: clamp(2rem, 4vw, 2.75rem);
  line-height: 1.25;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}
.hero-lead { color: var(--muted); font-size: 1.1rem; margin-bottom: 24px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}
.btn-primary {
  background: linear-gradient(120deg, var(--primary), var(--accent));
  color: #fff;
  box-shadow: 0 8px 24px rgba(37,99,235,0.35);
}
.btn-outline {
  background: var(--surface);
  color: var(--primary);
  border: 1px solid var(--border);
}
.btn:hover { transform: translateY(-2px); }
.hero-visual img {
  width: 100%;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.section { padding: 56px 0; }
.section-head { margin-bottom: 28px; }
.section-head h2 { font-size: 1.75rem; margin-bottom: 8px; }
.section-head p { color: var(--muted); }
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
  display: flex;
  flex-direction: column;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: #bfdbfe;
}
.card-thumb { aspect-ratio: 16/9; overflow: hidden; background: #eef2ff; }
.card-thumb img { width: 100%; height: 100%; object-fit: cover; }
.card-body { padding: 18px; flex: 1; display: flex; flex-direction: column; }
.card-tag {
  display: inline-block;
  font-size: 0.75rem;
  color: var(--accent);
  background: #f3e8ff;
  padding: 4px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
  width: fit-content;
}
.card h3 { font-size: 1.05rem; margin-bottom: 8px; line-height: 1.4; }
.card h3 a { color: inherit; }
.card p { color: var(--muted); font-size: 0.92rem; flex: 1; }
.download-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}
.download-tile {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  text-align: center;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.download-tile:hover {
  border-color: #93c5fd;
  box-shadow: var(--shadow);
}
.download-tile .icon { font-size: 2.5rem; margin-bottom: 12px; }
.download-tile h3 { margin-bottom: 8px; }
.download-tile p { color: var(--muted); font-size: 0.9rem; margin-bottom: 16px; }
.info-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  margin-top: 24px;
}
.tag-cloud { display: flex; flex-wrap: wrap; gap: 10px; }
.tag-cloud a {
  padding: 6px 14px;
  background: #eff6ff;
  border-radius: 999px;
  color: var(--primary-dark);
  font-size: 0.9rem;
}
.category-pills { display: flex; flex-wrap: wrap; gap: 10px; margin-bottom: 24px; }
.category-pills a {
  padding: 8px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text);
}
.category-pills a:hover { border-color: #93c5fd; background: #eff6ff; }
.article-body h2 { margin: 2rem 0 1rem; font-size: 1.4rem; color: var(--primary-dark); }
.article-body h3 { margin: 1.5rem 0 0.75rem; font-size: 1.15rem; }
.article-body p { margin-bottom: 1rem; text-align: justify; }
.article-body img {
  max-width: 100%;
  border-radius: var(--radius);
  margin: 1.5rem 0;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
}
.article-body ul { margin: 1rem 0 1rem 1.25rem; }
.nav-prev-next {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 32px;
}
.nav-prev-next a {
  padding: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text);
}
.nav-prev-next .label { font-size: 0.8rem; color: var(--muted); display: block; margin-bottom: 4px; }
.site-footer {
  background: #0f172a;
  color: rgba(255,255,255,0.85);
  padding: 48px 0 28px;
  margin-top: 48px;
}
.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 28px;
}
.site-footer h4 { color: #fff; margin-bottom: 12px; }
.site-footer a { color: rgba(255,255,255,0.75); display: block; line-height: 2; }
.site-footer a:hover { color: #93c5fd; }
.footer-bottom {
  text-align: center;
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px solid rgba(255,255,255,0.1);
  font-size: 0.9rem;
  color: rgba(255,255,255,0.5);
}
.breadcrumb { padding: 20px 0 0; font-size: 0.9rem; color: var(--muted); }
.breadcrumb a { color: var(--primary); }
@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; }
  .download-grid { grid-template-columns: 1fr; }
  .site-nav ul { gap: 4px; }
  .site-nav a { padding: 6px 10px; font-size: 0.9rem; }
  .nav-prev-next { grid-template-columns: 1fr; }
}