:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --ink: #1d2733;
  --muted: #5a6b7b;
  --accent: #1f7a8c;
  --accent-dark: #145863;
  --border: #e3e8ee;
  --radius: 12px;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", Roboto, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
}
.container { width: min(960px, 92vw); margin: 0 auto; }
.hero {
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent-dark) 100%);
  color: #fff;
  padding: 64px 0 56px;
}
.hero-inner { position: relative; }
.hero h1 { margin: 0 0 12px; font-size: clamp(1.8rem, 4vw, 2.6rem); }
.hero-sub { margin: 0; font-size: 1.1rem; opacity: 0.92; }
.lang-toggle {
  position: absolute; top: 0; right: 0;
  background: rgba(255,255,255,0.16); color: #fff;
  border: 1px solid rgba(255,255,255,0.5);
  padding: 6px 16px; border-radius: 999px; cursor: pointer; font-size: 0.9rem;
}
.lang-toggle:hover { background: rgba(255,255,255,0.28); }
.block { margin: 40px 0; }
.block h2 { font-size: 1.5rem; border-left: 4px solid var(--accent); padding-left: 12px; }
.structure-table { width: 100%; border-collapse: collapse; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.structure-table th, .structure-table td { text-align: left; padding: 12px 16px; border-bottom: 1px solid var(--border); vertical-align: top; }
.structure-table thead th { background: #eef3f5; color: var(--muted); font-weight: 600; }
.structure-table tr:last-child td { border-bottom: none; }
code { background: #eef3f5; padding: 1px 6px; border-radius: 6px; font-size: 0.88em; }
.download-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 20px; }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; display: flex; flex-direction: column; }
.card h3 { margin: 0 0 6px; font-size: 1.15rem; }
.card-file { margin: 0 0 10px; }
.card-desc { color: var(--muted); flex: 1; margin: 0 0 16px; font-size: 0.95rem; }
.card-stats { display: flex; gap: 18px; font-size: 0.9rem; color: var(--muted); margin-bottom: 14px; }
.card-stats strong { color: var(--accent-dark); }
.download-btn { background: var(--accent); color: #fff; border: none; padding: 10px 16px; border-radius: 8px; cursor: pointer; font-size: 0.95rem; }
.download-btn:hover { background: var(--accent-dark); }
.privacy { background: #fff7ed; border: 1px solid #fcd9a8; border-radius: var(--radius); padding: 8px 24px 20px; }
.privacy h2 { border-left-color: #e08a00; }
.cite { background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 12px 16px; font-size: 0.92rem; }
.site-footer { border-top: 1px solid var(--border); margin-top: 48px; padding: 24px 0; color: var(--muted); font-size: 0.9rem; }