/* ============================================================
   B2B Site Cluster — Shared Base Stylesheet
   每个站通过 :root 里的 CSS 变量做差异化配色，其余复用
   ============================================================ */
:root {
  --brand: #0e5fd8;          /* 主色：每站换一个 */
  --brand-dark: #0a4394;
  --brand-light: #e8f0fe;
  --accent: #ff7a00;         /* CTA 强调色 */
  --ink: #1c2330;
  --ink-soft: #5a6572;
  --bg: #ffffff;
  --bg-soft: #f5f7fa;
  --line: #e3e7ec;
  --radius: 10px;
  --maxw: 1120px;
  --font: "Segoe UI", "Helvetica Neue", Arial, "PingFang SC", sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { font-family: var(--font); color: var(--ink); background: var(--bg); line-height: 1.65; font-size: 16px; }
img { max-width: 100%; display: block; }
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }

/* ---------- Header / Nav ---------- */
.site-header { position: sticky; top: 0; background: #fff; border-bottom: 1px solid var(--line); z-index: 50; }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { font-size: 20px; font-weight: 800; color: var(--ink); display: flex; align-items: center; gap: 8px; }
.logo:hover { text-decoration: none; }
.logo .mark { width: 28px; height: 28px; border-radius: 6px; background: var(--brand); display: inline-block; }
.nav { display: flex; gap: 26px; align-items: center; }
.nav a { color: var(--ink); font-weight: 600; font-size: 15px; }
.nav a:hover { color: var(--brand); text-decoration: none; }
.nav .btn-nav { background: var(--accent); color: #fff; padding: 8px 18px; border-radius: var(--radius); }
.nav .btn-nav:hover { filter: brightness(1.08); text-decoration: none; }
.nav-toggle { display: none; background: none; border: none; font-size: 24px; cursor: pointer; color: var(--ink); }

/* ---------- Hero ---------- */
.hero { background: linear-gradient(135deg, var(--brand-dark), var(--brand)); color: #fff; padding: 72px 0 80px; }
.hero h1 { font-size: 40px; line-height: 1.2; margin-bottom: 16px; max-width: 720px; }
.hero p { font-size: 18px; opacity: .92; max-width: 640px; margin-bottom: 28px; }
.hero .btn { display: inline-block; background: var(--accent); color: #fff; font-weight: 700; padding: 13px 30px; border-radius: var(--radius); font-size: 16px; }
.hero .btn:hover { text-decoration: none; filter: brightness(1.08); }
.hero .btn.ghost { background: transparent; border: 2px solid rgba(255,255,255,.7); margin-left: 12px; }
.hero-badges { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 34px; }
.hero-badges span { background: rgba(255,255,255,.14); padding: 7px 15px; border-radius: 20px; font-size: 13.5px; }

/* ---------- Sections ---------- */
section { padding: 64px 0; }
section.alt { background: var(--bg-soft); }
.sec-head { text-align: center; margin-bottom: 42px; }
.sec-head h2 { font-size: 30px; margin-bottom: 10px; }
.sec-head p { color: var(--ink-soft); max-width: 620px; margin: 0 auto; }

/* ---------- Product grid ---------- */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 22px; }
.card { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; transition: box-shadow .2s, transform .2s; }
.card:hover { box-shadow: 0 8px 24px rgba(20,30,50,.10); transform: translateY(-3px); }
.card .thumb { aspect-ratio: 4/3; background: linear-gradient(135deg, var(--brand-light), #d5e3fb); display: flex; align-items: center; justify-content: center; color: var(--brand-dark); font-weight: 700; font-size: 14px; }
.card .body { padding: 16px 18px 20px; }
.card h3 { font-size: 16.5px; margin-bottom: 6px; }
.card h3 a { color: var(--ink); }
.card .meta { color: var(--ink-soft); font-size: 13.5px; }

/* ---------- Feature list ---------- */
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 26px; }
.feature { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 26px; }
.feature .icon { font-size: 30px; margin-bottom: 12px; }
.feature h3 { font-size: 17px; margin-bottom: 8px; }
.feature p { color: var(--ink-soft); font-size: 14.5px; }

/* ---------- Trust / numbers ---------- */
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 18px; text-align: center; }
.stats b { font-size: 32px; color: var(--brand); display: block; }
.stats span { color: var(--ink-soft); font-size: 14px; }

/* ---------- CTA band ---------- */
.cta-band { background: var(--ink); color: #fff; text-align: center; padding: 56px 0; }
.cta-band h2 { font-size: 26px; margin-bottom: 12px; }
.cta-band .btn { display: inline-block; background: var(--accent); color: #fff; font-weight: 700; padding: 12px 30px; border-radius: var(--radius); margin-top: 8px; }
.cta-band .btn:hover { text-decoration: none; filter: brightness(1.08); }

/* ---------- Forms ---------- */
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.form-grid .full { grid-column: 1 / -1; }
label { font-weight: 600; font-size: 14px; display: block; margin-bottom: 6px; }
input, select, textarea { width: 100%; padding: 11px 13px; border: 1px solid var(--line); border-radius: 8px; font-family: inherit; font-size: 15px; }
input:focus, select:focus, textarea:focus { outline: 2px solid var(--brand); border-color: transparent; }
.btn-primary { background: var(--accent); color: #fff; border: none; font-weight: 700; padding: 13px 32px; border-radius: var(--radius); font-size: 16px; cursor: pointer; }
.btn-primary:hover { filter: brightness(1.08); }

/* ---------- FAQ ---------- */
.faq details { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 20px; margin-bottom: 12px; }
.faq summary { font-weight: 700; cursor: pointer; }
.faq p { color: var(--ink-soft); margin-top: 10px; font-size: 15px; }

/* ---------- Footer ---------- */
.site-footer { background: var(--ink); color: #c8cfda; padding: 48px 0 28px; font-size: 14.5px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 30px; margin-bottom: 30px; }
.site-footer h4 { color: #fff; font-size: 15px; margin-bottom: 12px; }
.site-footer a { color: #c8cfda; display: block; margin-bottom: 8px; }
.site-footer a:hover { color: #fff; }
.copyright { border-top: 1px solid rgba(255,255,255,.12); padding-top: 20px; text-align: center; font-size: 13px; color: #8d97a6; }

/* ---------- Responsive ---------- */
@media (max-width: 800px) {
  .hero h1 { font-size: 30px; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .nav { position: fixed; top: 64px; right: -100%; flex-direction: column; background: #fff; width: 260px; height: calc(100vh - 64px); padding: 26px; box-shadow: -6px 0 20px rgba(0,0,0,.08); transition: right .25s; align-items: flex-start; }
  .nav.open { right: 0; }
  .nav-toggle { display: block; }
  .form-grid { grid-template-columns: 1fr; }
}