/* 基础变量与重置 */
:root {
  --brand: #0f766e;
  --brand-dark: #0a4f4b;
  --accent: #3b82f6;
  --bg: #f8fafc;
  --text: #0f172a;
  --muted: #64748b;
  --card: #ffffff;
  --border: #e2e8f0;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body { font-family: system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Hiragino Sans", "Microsoft YaHei"; color: var(--text); background: var(--bg); line-height: 1.6; }
img { max-width: 100%; display: block; }
.container { width: min(1100px, 92%); margin: 0 auto; }

/* 头部导航 */
.site-header { position: sticky; top: 0; z-index: 100; background: #fff; border-bottom: 1px solid var(--border); }
.header-inner { display: flex; align-items: center; justify-content: space-between; padding: 12px 0; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; color: var(--text); }
.brand .logo { width: 36px; height: 36px; }
.brand-name { font-weight: 700; letter-spacing: 0.5px; }
.nav-toggle { display: none; background: var(--brand); color: #fff; border: none; padding: 8px 12px; border-radius: 6px; }
.nav-menu { list-style: none; display: flex; gap: 18px; margin: 0; padding: 0; }
.nav-menu a { color: var(--text); text-decoration: none; padding: 8px 6px; border-radius: 6px; }
.nav-menu a:hover, .nav-menu a.active { background: var(--bg); color: var(--brand); }

/* Hero */
.hero { background: linear-gradient(135deg, #ecfeff, #f0f9ff); border-bottom: 1px solid var(--border); }
.hero-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 32px; align-items: center; padding: 48px 0; }
.hero h1 { font-size: clamp(28px, 4.5vw, 42px); margin: 0 0 12px; }
.hero p { color: var(--muted); margin: 0 0 20px; }
.hero-actions { display: flex; gap: 12px; }
.btn { display: inline-block; padding: 10px 16px; border-radius: 8px; text-decoration: none; font-weight: 600; }
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); }
.btn-outline { border: 1px solid var(--brand); color: var(--brand); }
.btn-outline:hover { background: #ecfeff; }
.hero-art img { width: 100%; }

/* sections */
.section-title { font-size: 22px; margin: 36px 0 18px; }
.features .grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 18px; box-shadow: 0 4px 14px rgba(0,0,0,0.04); }
.card h3 { margin: 10px 0; font-size: 18px; }
.card p { color: var(--muted); margin: 0; }

/* CTA */
.cta { background: #fff; border-top: 1px solid var(--border); }
.cta-inner { text-align: center; padding: 36px 0; }
.cta h2 { margin: 0 0 8px; font-size: 24px; }
.cta p { color: var(--muted); margin: 0 0 16px; }

/* 页面头 */
.page-hero { background: #fff; border-bottom: 1px solid var(--border); }
.page-hero .container { padding: 24px 0; }

/* 内容区 */
.content-section { padding: 24px 0; }
.list { margin: 10px 0 0 20px; }
.policy h2 { margin-top: 16px; }

/* 联系表单 */
.form { display: grid; gap: 14px; }
.form-row { display: grid; gap: 6px; }
.form-row input, .form-row textarea { padding: 10px; border: 1px solid var(--border); border-radius: 8px; font: inherit; }
.form-row input:focus, .form-row textarea:focus { outline: none; border-color: var(--brand); box-shadow: 0 0 0 3px rgba(15,118,110,0.12); }
.error { color: #b91c1c; min-height: 18px; }
.form-actions { display: flex; align-items: center; gap: 12px; }
.form-tip { color: var(--muted); }

/* 页脚 */
.site-footer { background: #fff; border-top: 1px solid var(--border); margin-top: 28px; }
.footer-inner { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 12px; padding: 16px 0; }
.footer-brand { display: inline-flex; gap: 10px; align-items: center; }
.footer-brand .logo { width: 28px; height: 28px; }
.footer-links { list-style: none; display: flex; gap: 12px; margin: 0; padding: 0; }
.footer-links a { color: var(--muted); text-decoration: none; }
.footer-links a:hover, .footer-links a.active { color: var(--brand); }

/* 响应式 */
@media (max-width: 960px) {
  .hero-inner { grid-template-columns: 1fr; }
  .features .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .nav-toggle { display: inline-block; }
  .nav-menu { position: absolute; right: 4%; top: 60px; background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 8px; display: none; flex-direction: column; gap: 8px; box-shadow: 0 6px 20px rgba(0,0,0,0.06); }
  .nav-menu.open { display: flex; }
  .features .grid-4, .grid-3 { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; text-align: center; }
}