/* ============================================================
   比特浏览器 - 全站共享样式
   Bing GEO 2026 合规模板
   ============================================================ */
:root {
  --primary: #0d9488;
  --primary-dark: #0f766e;
  --primary-light: #f0fdfa;
  --accent: #10b981;
  --gradient: linear-gradient(135deg, #0d9488 0%, #10b981 100%);
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #0f172a;
  --text-secondary: #64748b;
  --border: #e2e8f0;
  --success: #16a34a;
  --warning: #d97706;
  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 4px 20px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 12px 40px rgba(13, 148, 136, 0.14);
  --container: 1200px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img, svg { display: block; max-width: 100%; }
a { color: var(--primary); text-decoration: none; }
ul, ol { list-style: none; }
button { font-family: inherit; cursor: pointer; }

.container { max-width: var(--container); margin: 0 auto; padding: 0 24px; }

/* ---------- 顶部导航 ---------- */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  transition: box-shadow 0.3s;
}
.header.scrolled { box-shadow: 0 4px 16px rgba(15, 23, 42, 0.08); }
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}
.logo { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 20px; color: var(--text); }
.logo svg, .logo-icon { width: 30px; height: 30px; }
.logo span em { font-style: normal; color: var(--primary); }

.nav { display: flex; align-items: center; gap: 28px; }
.nav a { color: var(--text-secondary); font-size: 15px; font-weight: 500; transition: color 0.2s; }
.nav a:hover, .nav a.active { color: var(--primary); }
.nav-cta { margin-left: 8px; }
.nav a.btn-primary, .nav a.btn-primary:visited, .nav a.btn-primary:hover, .nav a.btn-primary:focus { color: #fff; }
.nav a.btn-outline, .nav a.btn-outline:visited, .nav a.btn-outline:hover, .nav a.btn-outline:focus { color: var(--primary); }

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  width: 42px;
  height: 42px;
  align-items: center;
  justify-content: center;
}
.nav-toggle span { display: block; width: 18px; height: 2px; background: var(--text); margin: 2.5px 0; border-radius: 2px; transition: 0.3s; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  border: 1px solid transparent;
  transition: all 0.25s;
  white-space: nowrap;
}
.btn-primary {
  background: #1a56db;
  color: #ffffff;
  font-weight: 800;
  letter-spacing: 0.5px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
  box-shadow: 0 6px 18px rgba(26, 86, 219, 0.45);
}
.btn-primary:hover { background: #1e40af; transform: translateY(-2px); box-shadow: 0 10px 24px rgba(26, 86, 219, 0.5); }
.btn-outline { background: transparent; color: var(--primary); border-color: var(--primary); }
.btn-outline:hover { background: var(--primary-light); }
.btn-lg { padding: 15px 34px; font-size: 16px; border-radius: 10px; }
.btn-block { width: 100%; }

/* ---------- 通用区块 ---------- */
.section { padding: 88px 0; }
.section-header { text-align: center; max-width: 720px; margin: 0 auto 52px; }
.section-tag {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  color: var(--primary);
  background: var(--primary-light);
  border-radius: 999px;
  padding: 5px 14px;
  margin-bottom: 16px;
}
.section-title { font-size: 34px; font-weight: 800; letter-spacing: -0.5px; }
.section-sub { margin-top: 14px; color: var(--text-secondary); font-size: 16px; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  overflow: hidden;
  background: linear-gradient(180deg, #f0f6ff 0%, #e8f3ff 45%, #f8fafc 100%);
  padding: 96px 0 80px;
}
.hero::before {
  content: "";
  position: absolute;
  width: 560px;
  height: 560px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(26, 86, 219, 0.10), transparent 65%);
  top: -180px;
  right: -120px;
}
.hero-grid { display: grid; grid-template-columns: 0.95fr 1.15fr; gap: 44px; align-items: center; position: relative; z-index: 1; }
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 600;
  color: var(--primary);
  background: #fff;
  border: 1px solid #d6e4ff;
  padding: 6px 14px;
  border-radius: 999px;
  margin-bottom: 22px;
}
.hero h1 { font-size: 46px; font-weight: 800; line-height: 1.22; letter-spacing: -1px; }
.hero h1 em { font-style: normal; color: var(--primary); }
.hero-desc { margin: 22px 0 30px; font-size: 17px; color: var(--text-secondary); max-width: 540px; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; }

.hero-stats {
  display: flex;
  gap: 40px;
  margin-top: 46px;
  padding-top: 34px;
  border-top: 1px solid rgba(100, 116, 139, 0.18);
  flex-wrap: wrap;
}
.hero-stat strong { display: block; font-size: 28px; font-weight: 800; color: var(--primary-dark); }
.hero-stat span { font-size: 13.5px; color: var(--text-secondary); }

/* Hero 产品展示框 */
.hero-visual { position: relative; }
.browser-mock {
  background: #fff;
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
  overflow: hidden;
}
.mock-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  background: #fbfdff;
}
.mock-bar i { width: 11px; height: 11px; border-radius: 50%; }
.mock-bar i:nth-child(1) { background: #f87171; }
.mock-bar i:nth-child(2) { background: #fbbf24; }
.mock-bar i:nth-child(3) { background: #34d399; }
.mock-bar .mock-url {
  flex: 1;
  margin-left: 12px;
  background: #f1f5f9;
  border-radius: 6px;
  font-size: 12.5px;
  color: var(--text-secondary);
  padding: 5px 12px;
}
.mock-body { padding: 20px; }
.mock-head { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; }
.mock-head h4 { font-size: 14px; }
.mock-tag { font-size: 11.5px; background: #ecfdf5; color: #059669; padding: 3px 10px; border-radius: 999px; font-weight: 600; }
.mock-list { display: flex; flex-direction: column; gap: 10px; }
.mock-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: #fff;
}
.mock-row .dot { width: 30px; height: 30px; border-radius: 8px; background: var(--gradient); flex-shrink: 0; }
.mock-row .txt { flex: 1; }
.mock-row .txt b { font-size: 13px; font-weight: 600; }
.mock-row .txt span { font-size: 12px; color: var(--text-secondary); }
.mock-row .flag { font-size: 11.5px; color: var(--success); font-weight: 600; }
.float-card {
  position: absolute;
  right: -18px;
  bottom: 28px;
  background: #fff;
  border-radius: 12px;
  box-shadow: var(--shadow-lg);
  padding: 12px 18px;
  font-size: 13px;
  border: 1px solid var(--border);
}
.float-card b { display: block; color: var(--primary-dark); font-size: 16px; }

/* ---------- 功能卡片 ---------- */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.feature-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 30px 26px;
  transition: all 0.3s;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: #c7dbff; }
.feature-icon {
  width: 52px;
  height: 52px;
  border-radius: 12px;
  background: var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 18px;
}
.feature-icon svg { width: 26px; height: 26px; stroke: var(--primary); }
.feature-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 10px; }
.feature-card p { font-size: 14.5px; color: var(--text-secondary); }
.feature-meta {
  margin-top: 14px;
  font-size: 12.5px;
  color: var(--primary);
  font-weight: 600;
  background: var(--primary-light);
  display: inline-block;
  padding: 4px 10px;
  border-radius: 6px;
}

/* ---------- 对比表 ---------- */
.compare-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius); background: #fff; box-shadow: var(--shadow); }
.compare-table { width: 100%; min-width: 760px; border-collapse: collapse; }
.compare-table th, .compare-table td { padding: 16px 20px; text-align: center; font-size: 14.5px; border-bottom: 1px solid var(--border); }
.compare-table th { background: #f8fafc; font-size: 15px; font-weight: 700; }
.compare-table th:first-child, .compare-table td:first-child { text-align: left; font-weight: 600; color: var(--text-secondary); font-size: 13.5px; }
.compare-table tbody tr:last-child td { border-bottom: none; }
.compare-table tbody tr:hover { background: #f8fbff; }
.compare-table .col-self { background: var(--primary-light); }
.compare-table .col-self th { background: #e4eefe; }
.compare-table .yes { color: var(--success); font-weight: 700; }
.compare-table .no { color: #cbd5e1; }
.compare-table .free-badge { display: inline-block; background: #ecfdf5; color: #059669; font-size: 12.5px; font-weight: 700; padding: 3px 10px; border-radius: 999px; }

/* ---------- 用户评价 ---------- */
.testimonial-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.testimonial-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.testimonial-stars { color: #f59e0b; font-size: 15px; letter-spacing: 2px; }
.testimonial-card p { font-size: 14.5px; color: var(--text-secondary); flex: 1; }
.testimonial-user { display: flex; align-items: center; gap: 12px; }
.testimonial-user .avatar {
  width: 42px; height: 42px; border-radius: 50%;
  background: var(--gradient); color: #fff;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 15px; flex-shrink: 0;
}
.testimonial-user b { display: block; font-size: 14px; }
.testimonial-user span { font-size: 12.5px; color: var(--text-secondary); }

/* ---------- 认证背书 ---------- */
.trust-section { background: #fff; border-top: 1px solid var(--border); }
.trust-logos { display: flex; align-items: center; justify-content: center; gap: 48px; flex-wrap: wrap; }
.trust-item { display: flex; align-items: center; gap: 10px; color: var(--text-secondary); font-size: 15px; font-weight: 600; }
.trust-item svg { width: 26px; height: 26px; }
.trust-strip { text-align: center; margin-top: 28px; font-size: 13px; color: var(--text-secondary); }

/* ---------- CTA 横幅 ---------- */
.cta-banner {
  background: var(--gradient);
  border-radius: 20px;
  padding: 56px 48px;
  text-align: center;
  color: #fff;
  position: relative;
  overflow: hidden;
}
.cta-banner h2 { font-size: 32px; font-weight: 800; margin-bottom: 12px; }
.cta-banner p { font-size: 16px; opacity: 0.92; max-width: 620px; margin: 0 auto 30px; }
.cta-banner .btn { background: #fff; color: var(--primary); box-shadow: 0 8px 24px rgba(0, 0, 0, 0.16); }
.cta-banner .btn:hover { transform: translateY(-2px); }
.cta-note { margin-top: 16px; font-size: 13px; opacity: 0.85; }

/* ---------- FAQ ---------- */
.faq-list { max-width: 800px; margin: 0 auto; display: flex; flex-direction: column; gap: 14px; }
.faq-item {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.faq-item summary {
  list-style: none;
  cursor: pointer;
  padding: 20px 24px;
  font-size: 16px;
  font-weight: 600;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+";
  font-size: 22px;
  color: var(--primary);
  font-weight: 400;
  transition: transform 0.3s;
  flex-shrink: 0;
}
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item .faq-body { padding: 0 24px 20px; color: var(--text-secondary); font-size: 14.5px; }

/* ---------- 页脚 ---------- */
.footer { background: #0b1220; color: #94a3b8; padding: 64px 0 0; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 40px; padding-bottom: 44px; }
.footer h4 { color: #fff; font-size: 15px; margin-bottom: 16px; }
.footer a { color: #94a3b8; font-size: 14px; display: block; padding: 5px 0; transition: color 0.2s; }
.footer a:hover { color: #fff; }
.footer-brand p { font-size: 13.5px; margin-top: 14px; max-width: 280px; }
.footer-bottom {
  border-top: 1px solid rgba(148, 163, 184, 0.15);
  padding: 20px 0;
  font-size: 13px;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

/* ============================================================
   下载页
   ============================================================ */
.page-hero {
  background: linear-gradient(180deg, #f0f6ff 0%, #f8fafc 100%);
  padding: 72px 0 60px;
  text-align: center;
}
.page-hero h1 { font-size: 40px; font-weight: 800; letter-spacing: -0.5px; }
.page-hero .page-desc { max-width: 640px; margin: 16px auto 0; color: var(--text-secondary); font-size: 16px; }
.breadcrumb {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
  background: #fff;
  border: 1px solid var(--border);
  padding: 6px 16px;
  border-radius: 999px;
  margin-bottom: 22px;
}
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--primary); }

.version-bar {
  display: inline-flex;
  align-items: center;
  gap: 18px;
  margin-top: 26px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 24px;
  font-size: 13.5px;
  color: var(--text-secondary);
  flex-wrap: wrap;
  justify-content: center;
}
.version-bar .vs { color: var(--success); font-weight: 600; }

.platform-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 20px; }
.platform-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  transition: all 0.3s;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}
.platform-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: #c7dbff; }
.platform-card .p-icon {
  width: 64px; height: 64px;
  border-radius: 16px;
  background: var(--primary-light);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 6px;
}
.platform-card .p-icon svg { width: 32px; height: 32px; stroke: var(--primary); }
.platform-card h3 { font-size: 17px; font-weight: 700; }
.platform-card p { font-size: 12.5px; color: var(--text-secondary); min-height: 38px; }
.platform-card .btn { margin-top: 12px; padding: 9px 18px; font-size: 13.5px; }

.steps { counter-reset: step; display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.step-item {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 24px;
  position: relative;
}
.step-item::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  top: -16px;
  left: 24px;
  width: 34px; height: 34px;
  background: var(--gradient);
  color: #fff;
  font-weight: 800;
  font-size: 16px;
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 6px 14px rgba(26, 86, 219, 0.3);
}
.step-item h3 { font-size: 16px; font-weight: 700; margin: 14px 0 8px; }
.step-item p { font-size: 13.5px; color: var(--text-secondary); }

.spec-table { width: 100%; border-collapse: collapse; background: #fff; border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.spec-table th, .spec-table td { padding: 16px 24px; border-bottom: 1px solid var(--border); font-size: 14.5px; text-align: left; }
.spec-table th { width: 200px; background: #f8fafc; font-weight: 600; color: var(--text-secondary); }
.spec-table tr:last-child td, .spec-table tr:last-child th { border-bottom: none; }
.spec-note { margin-top: 14px; font-size: 12.5px; color: var(--text-secondary); }

/* ============================================================
   资讯页
   ============================================================ */
.news-layout { display: grid; grid-template-columns: 1fr 340px; gap: 40px; align-items: start; }
.tag-list { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 34px; }
.tag-list a {
  font-size: 13.5px;
  font-weight: 600;
  color: var(--text-secondary);
  padding: 7px 18px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: #fff;
  transition: all 0.2s;
}
.tag-list a:hover, .tag-list a.active { color: #fff; background: var(--gradient); border-color: transparent; }

.news-grid { display: flex; flex-direction: column; gap: 24px; }
.article-card {
  display: flex;
  gap: 24px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all 0.3s;
}
.article-card:hover { box-shadow: var(--shadow-lg); transform: translateY(-3px); border-color: #c7dbff; }
.article-thumb {
  width: 220px;
  flex-shrink: 0;
  border-radius: var(--radius-sm);
  background: var(--gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgba(255, 255, 255, 0.85);
  font-size: 13px;
  font-weight: 600;
  min-height: 140px;
}
.article-thumb.t2 { background: linear-gradient(135deg, #0ea5e9, #22d3ee); }
.article-thumb.t3 { background: linear-gradient(135deg, #8b5cf6, #6366f1); }
.article-thumb.t4 { background: linear-gradient(135deg, #f59e0b, #f97316); }
.article-card .a-meta { display: flex; gap: 16px; font-size: 12.5px; color: var(--text-secondary); margin-bottom: 10px; align-items: center; }
.article-card .a-cat { font-size: 12px; font-weight: 700; color: var(--primary); background: var(--primary-light); padding: 3px 10px; border-radius: 6px; }
.article-card h3 { font-size: 19px; font-weight: 700; line-height: 1.4; margin-bottom: 10px; }
.article-card h3 a { color: var(--text); }
.article-card h3 a:hover { color: var(--primary); }
.article-card .a-excerpt { font-size: 14px; color: var(--text-secondary); margin-bottom: 14px; }
.article-card .a-more { font-size: 13.5px; font-weight: 600; }

.sidebar { display: flex; flex-direction: column; gap: 24px; position: sticky; top: 88px; }
.side-card { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; }
.side-card h3 { font-size: 16px; font-weight: 700; padding-bottom: 14px; margin-bottom: 6px; border-bottom: 2px solid var(--primary-light); position: relative; }
.side-card h3::after { content: ""; position: absolute; left: 0; bottom: -2px; width: 44px; height: 2px; background: var(--primary); }
.hot-list { display: flex; flex-direction: column; }
.hot-item { display: flex; gap: 12px; padding: 14px 0; border-bottom: 1px dashed var(--border); align-items: flex-start; }
.hot-item:last-child { border-bottom: none; }
.hot-num { font-size: 20px; font-weight: 800; color: #cbd5e1; line-height: 1; flex-shrink: 0; width: 26px; }
.hot-item:nth-child(-n+3) .hot-num { color: var(--primary); }
.hot-item h4 { font-size: 14px; font-weight: 600; line-height: 1.5; }
.hot-item h4 a { color: var(--text); }
.hot-item h4 a:hover { color: var(--primary); }
.hot-item span { font-size: 12px; color: var(--text-secondary); margin-top: 4px; display: block; }

.subscribe-box { background: var(--gradient); color: #fff; border: none; text-align: center; }
.subscribe-box h3 { color: #fff; border-color: rgba(255, 255, 255, 0.3); }
.subscribe-box h3::after { background: #fff; }
.subscribe-box p { font-size: 13.5px; opacity: 0.92; margin: 8px 0 18px; }
.subscribe-box form { display: flex; flex-direction: column; gap: 10px; }
.subscribe-box input {
  border: none;
  border-radius: 8px;
  padding: 12px 14px;
  font-size: 14px;
  width: 100%;
  outline: none;
}
.subscribe-box .btn { background: #fff; color: var(--primary); width: 100%; }

.pagination { display: flex; justify-content: center; gap: 8px; margin-top: 40px; }
.pagination a, .pagination span {
  width: 42px; height: 42px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 10px;
  background: #fff;
  border: 1px solid var(--border);
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
}
.pagination .current { background: var(--gradient); color: #fff; border-color: transparent; }

/* ---------- 返回顶部 ---------- */
.back-top {
  position: fixed;
  right: 26px;
  bottom: 26px;
  width: 46px; height: 46px;
  border-radius: 12px;
  background: var(--gradient);
  color: #fff;
  border: none;
  font-size: 20px;
  box-shadow: 0 8px 20px rgba(26, 86, 219, 0.35);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all 0.3s;
  z-index: 90;
}
.back-top.show { opacity: 1; visibility: visible; transform: translateY(0); }

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1024px) {
  .hero-grid { grid-template-columns: 1fr; gap: 40px; }
  .hero-visual { max-width: 560px; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .platform-grid { grid-template-columns: repeat(3, 1fr); }
  .steps { grid-template-columns: repeat(2, 1fr); }
  .news-layout { grid-template-columns: 1fr; }
  .sidebar { position: static; }
  .testimonial-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .section { padding: 60px 0; }
  .section-title { font-size: 26px; }
  .hero { padding: 60px 0 56px; }
  .hero h1 { font-size: 32px; }
  .nav {
    position: fixed;
    inset: 68px 0 auto 0;
    background: #fff;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 12px 24px 24px;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 16px 40px rgba(15, 23, 42, 0.1);
    transform: translateY(-120%);
    transition: transform 0.3s;
    z-index: 99;
  }
  .nav.open { transform: translateY(0); }
  .nav a { padding: 13px 0; border-bottom: 1px solid #f1f5f9; font-size: 16px; }
  .nav .btn { margin-top: 14px; }
  .nav-toggle { display: flex; flex-direction: column; }
  .nav-toggle.open span:nth-child(1) { transform: translateY(4.5px) rotate(45deg); }
  .nav-toggle.open span:nth-child(2) { opacity: 0; }
  .nav-toggle.open span:nth-child(3) { transform: translateY(-4.5px) rotate(-45deg); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .article-card { flex-direction: column; }
  .article-thumb { width: 100%; min-height: 120px; }
  .cta-banner { padding: 40px 24px; }
  .float-card { right: 6px; bottom: 10px; }
}

@media (max-width: 520px) {
  .feature-grid { grid-template-columns: 1fr; }
  .testimonial-grid { grid-template-columns: 1fr; }
  .platform-grid { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: 1fr; }
  .hero-stats { gap: 24px; }
  .hero-stat strong { font-size: 22px; }
  .footer-grid { grid-template-columns: 1fr; }
}

/* ============================================================
   文章详情页
   ============================================================ */
.article-layout { display: grid; grid-template-columns: 1fr 340px; gap: 40px; align-items: start; }
.article-main {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px 44px;
}
.article-head h1 { font-size: 30px; font-weight: 800; line-height: 1.35; letter-spacing: -0.3px; }
.article-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 18px 0 28px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--border);
  font-size: 13px;
  color: var(--text-secondary);
  flex-wrap: wrap;
}
.article-meta .a-cat { font-size: 12px; font-weight: 700; color: var(--primary); background: var(--primary-light); padding: 3px 10px; border-radius: 6px; }
.article-body { font-size: 15.5px; color: #334155; line-height: 1.9; }
.article-body h2 {
  font-size: 21px;
  font-weight: 800;
  margin: 34px 0 14px;
  padding-left: 14px;
  border-left: 4px solid var(--primary);
  line-height: 1.4;
}
.article-body h3 { font-size: 17px; font-weight: 700; margin: 26px 0 10px; }
.article-body p { margin-bottom: 16px; }
.article-body ul, .article-body ol { margin: 0 0 16px 4px; }
.article-body li { margin-bottom: 8px; padding-left: 4px; }
.article-body ul li { list-style: disc; margin-left: 20px; }
.article-body ol li { list-style: decimal; margin-left: 20px; }
.article-body strong { color: var(--text); }
.article-body blockquote {
  background: var(--primary-light);
  border-left: 4px solid var(--primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 14px 20px;
  margin: 20px 0;
  color: #1e40af;
  font-size: 14.5px;
}
.article-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  font-size: 14px;
}
.article-body th, .article-body td { border: 1px solid var(--border); padding: 10px 14px; text-align: left; }
.article-body th { background: #f8fafc; font-weight: 600; }
.article-tags { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 30px; padding-top: 22px; border-top: 1px solid var(--border); }
.article-tags span { font-size: 13px; color: var(--text-secondary); margin-right: 4px; }
.article-tags a { font-size: 12.5px; font-weight: 600; color: var(--primary); background: var(--primary-light); padding: 4px 12px; border-radius: 999px; }
.article-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 34px;
}
.article-nav a {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 20px;
  font-size: 13px;
  color: var(--text-secondary);
  transition: all 0.25s;
}
.article-nav a:hover { border-color: var(--primary); color: var(--primary); box-shadow: var(--shadow); }
.article-nav a b { display: block; font-size: 14.5px; color: var(--text); margin-top: 4px; }
.article-nav a:hover b { color: var(--primary); }
.article-nav .next { text-align: right; }

@media (max-width: 1024px) {
  .article-layout { grid-template-columns: 1fr; }
  .sidebar { position: static; }
}
@media (max-width: 768px) {
  .article-main { padding: 28px 22px; }
  .article-head h1 { font-size: 24px; }
  .article-nav { grid-template-columns: 1fr; }
  .article-nav .next { text-align: left; }
}

/* ---------- Hero 预览图 ---------- */
.hero-preview {
  display: block;
  width: 100%;
  height: auto;
  max-width: 680px;
  margin-inline: auto;
  border-radius: 18px;
  box-shadow: 0 30px 60px -20px rgba(15, 23, 42, 0.18), 0 18px 36px -18px rgba(26, 86, 219, 0.25);
  animation: floatY 6s ease-in-out infinite;
}

/* ---------- 表单提示 ---------- */
.form-tip { font-size: 13px; color: #fff; background: rgba(255, 255, 255, 0.18); padding: 8px 12px; border-radius: 8px; display: none; }
.form-tip.ok { display: block; color: #bbf7d0; }

/* ============================================================
   下载页版式
   ============================================================ */
.btn[disabled], .btn.disabled {
  background: #f1f5f9;
  color: #94a3b8;
  box-shadow: none;
  cursor: not-allowed;
  transform: none;
}
.btn[disabled]:hover { transform: none; box-shadow: none; }

.update-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.update-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 22px;
  transition: all 0.3s;
}
.update-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: #c7dbff; }
.update-icon {
  width: 48px; height: 48px;
  border-radius: 12px;
  background: var(--primary-light);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 16px;
}
.update-icon svg { width: 24px; height: 24px; stroke: var(--primary); }
.update-card h3 { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.update-card p { font-size: 13.5px; color: var(--text-secondary); }

.spec-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.spec-col {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 24px;
}
.spec-col h3 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 16px;
  padding-left: 12px;
  border-left: 4px solid var(--primary);
}
.spec-col .spec-table { border: none; }
.spec-col .spec-table th { width: 150px; }

@media (max-width: 1024px) {
  .update-grid { grid-template-columns: repeat(2, 1fr); }
  .spec-grid { grid-template-columns: 1fr; }
}
@media (max-width: 520px) {
  .update-grid { grid-template-columns: 1fr; }
}

/* Bing GEO 2026: accessibility & print */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}
@media print {
  .header, .footer, .nav-toggle, .back-top, .sidebar, .subscribe-box { display: none !important; }
  body { background: #fff !important; color: #000 !important; }
  .container, .section, .hero { max-width: 100% !important; padding: 0 !important; }
  a { color: #000; text-decoration: underline; }
  h1, h2, h3 { break-after: avoid; }
}