:root {
    --bg: #0a0a0f;
    --bg-card: #12121a;
    --bg-section: #0d0d14;
    --border: #1e1e2e;
    --border-soft: #232335;
    --text: #e4e4e7;
    --text-dim: #9ca3af;
    --text-bright: #fafafa;
    --accent: #0084ff;
    --accent-dim: #0066cc;
    --accent-glow: rgba(0, 132, 255, 0.14);
    --mock-win: #0f111a;
    --mock-bar: #151824;
    --mock-bubble: #1c1f2b;
    --warn-bg: rgba(245, 158, 11, 0.1);
    --warn-bd: rgba(245, 158, 11, 0.35);
    --radius: 14px;
    --radius-sm: 10px;
    --shadow-c: 0 12px 40px rgba(0, 0, 0, 0.45);
    --header-bg: rgba(10, 10, 15, 0.82);
    --grad-btn: linear-gradient(135deg, #0084ff 0%, #45bdff 100%);
  }
  /* ===== 浅色主题（根据时间自动 / 手动切换） ===== */
  html[data-theme="light"] {
    --bg: #f0f2f5;
    --bg-card: #ffffff;
    --bg-section: #e9edf2;
    --border: #e3e6ea;
    --border-soft: #d5dae0;
    --text: #2b2f36;
    --text-dim: #65676b;
    --text-bright: #16181c;
    --accent-glow: rgba(0, 132, 255, 0.12);
    --shadow-c: 0 12px 40px rgba(23, 60, 120, 0.12);
    --header-bg: rgba(255, 255, 255, 0.82);
    --mock-win: #f7f9fc;
    --mock-bar: #eef1f6;
    --mock-bubble: #e9eef5;
  }
  * { margin: 0; padding: 0; box-sizing: border-box; }
  html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }
  body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.75;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
  }
  a { color: inherit; text-decoration: none; }
  .container { max-width: 1120px; margin: 0 auto; padding: 0 24px; }
  h2 {
    font-size: 32px; font-weight: 800; color: var(--text-bright);
    letter-spacing: 0.5px;
  }
  .sub { color: var(--text-dim); font-size: 16px; margin-top: 10px; }
  .section-head { text-align: center; max-width: 640px; margin: 0 auto 48px; }
  .eyebrow {
    display: inline-block; font-size: 12px; font-weight: 700; letter-spacing: 2px;
    color: var(--accent); background: var(--accent-glow);
    padding: 5px 14px; border-radius: 999px; margin-bottom: 14px; text-transform: uppercase;
  }
  section { padding: 88px 0; position: relative; }
  .grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
  .grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
  @media (max-width: 860px) { .grid-3, .grid-2 { grid-template-columns: 1fr; } }

  /* ============ 按钮 ============ */
  .btn {
    display: inline-flex; align-items: center; gap: 8px;
    background: var(--grad-btn); color: #fff; font-weight: 700;
    padding: 13px 30px; border-radius: 999px; border: none; cursor: pointer;
    font-size: 15px; transition: transform .15s, box-shadow .15s;
    box-shadow: 0 8px 24px rgba(0, 132, 255, 0.3);
  }
  .btn:hover { transform: translateY(-2px); box-shadow: 0 12px 32px rgba(0, 132, 255, 0.4); }
  .btn-ghost {
    background: transparent; color: var(--text-bright);
    border: 1px solid var(--border-soft); box-shadow: none;
  }
  .btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

  /* ============ 导航 ============ */
  header {
    position: sticky; top: 0; z-index: 100;
    background: var(--header-bg); backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border);
  }
  .nav { display: flex; align-items: center; justify-content: space-between; height: 66px; }
  .nav-logo { display: flex; align-items: center; gap: 11px; font-weight: 800; color: var(--text-bright); font-size: 17px; }
  .nav-logo .mark {
    width: 34px; height: 34px; border-radius: 9px;
    background: var(--grad-btn); color: #fff; font-weight: 900;
    display: flex; align-items: center; justify-content: center; font-size: 18px;
    box-shadow: 0 4px 14px rgba(0,132,255,.4);
  }
  .nav-links { display: flex; gap: 30px; }
  .nav-links a { color: var(--text-dim); font-size: 14.5px; transition: color .15s; }
  .nav-links a:hover { color: var(--accent); }
  .nav .btn { padding: 9px 20px; font-size: 14px; }
  .nav-right { display: flex; align-items: center; gap: 12px; }
  .theme-btn {
    width: 38px; height: 38px; border-radius: 10px; border: 1px solid var(--border-soft);
    background: var(--bg-card); color: var(--text-dim); cursor: pointer;
    display: flex; align-items: center; justify-content: center;
    transition: color .2s, border-color .2s, transform .15s;
  }
  .theme-btn:hover { color: var(--accent); border-color: var(--accent); transform: translateY(-1px); }
  .theme-btn svg { width: 19px; height: 19px; }
  body, header, footer, .card, .step, .stat-card, .faq-item, .tabbtn, .shield, .dl-card, .theme-btn, .nav-logo, .nav-links a {
    transition: background-color .35s ease, border-color .35s ease, color .35s ease;
  }
  @media (max-width: 760px) { .nav-links { display: none; } }

  /* ============ Hero ============ */
  .hero { padding: 84px 0 72px; position: relative; overflow: hidden; }
  .hero::before {
    content: ""; position: absolute; inset: 0; pointer-events: none;
    background: radial-gradient(700px 380px at 70% -10%, rgba(0,132,255,.16), transparent 62%),
                radial-gradient(520px 320px at 10% 10%, rgba(69,189,255,.10), transparent 60%);
  }
  .hero .container { position: relative; }
  .hero-flex { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 48px; align-items: center; }
  @media (max-width: 860px) { .hero-flex { grid-template-columns: 1fr; } }
  .hero h1 { font-size: 46px; font-weight: 900; line-height: 1.22; color: var(--text-bright); letter-spacing: 1px; }
  .hero h1 em { font-style: normal; background: linear-gradient(90deg, #45bdff, #0084ff); -webkit-background-clip: text; background-clip: text; color: transparent; }
  .hero .h-sub { color: var(--text-dim); font-size: 17px; margin: 18px 0 30px; max-width: 460px; }
  .hero .cta-row { display: flex; gap: 14px; flex-wrap: wrap; }
  .hero .hint { color: var(--text-dim); font-size: 13px; margin-top: 14px; }
  .hero .hint a { color: var(--accent); }

  .stat-row {
    display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px;
    margin-top: 36px;
  }
  .stat-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius-sm); padding: 16px 14px; min-width: 0;
  }
  .stat-num { font-size: 26px; font-weight: 800; color: var(--accent); line-height: 1.2; }
  .stat-label { font-size: 12.5px; color: var(--text-dim); margin-top: 4px; }

  /* ============ Hero 界面 mockup ============ */
  .mock-wrap { perspective: 1200px; }
  .mock {
    position: relative; background: var(--mock-win); border: 1px solid var(--border-soft);
    border-radius: 16px; box-shadow: var(--shadow-c); overflow: hidden;
    transform: rotateY(-6deg) rotateX(2deg); transition: transform .3s;
  }
  .mock:hover { transform: rotateY(-2deg) rotateX(0deg); }
  .mock-bar {
    display: flex; align-items: center; gap: 6px;
    background: var(--mock-bar); padding: 11px 14px; border-bottom: 1px solid var(--border);
  }
  .mock-bar i { width: 11px; height: 11px; border-radius: 50%; display: block; }
  .mock-bar i:nth-child(1) { background: #ff5f57; }
  .mock-bar i:nth-child(2) { background: #febc2e; }
  .mock-bar i:nth-child(3) { background: #28c840; }
  .mock-bar .t { margin-left: 10px; font-size: 12px; color: var(--text-dim); }
  .mock-body { padding: 16px; }
  .mock-chat { display: flex; gap: 3px; flex-direction: column; }
  .m-row { display: flex; align-items: center; gap: 9px; margin-bottom: 14px; }
  .m-ava { width: 28px; height: 28px; border-radius: 8px; background: var(--accent-glow); display: flex; align-items: center; justify-content: center; font-size: 12px; color: var(--accent); font-weight: 700; flex: 0 0 auto; }
  .m-line { flex: 1; }
  .m-item { display: flex; margin-bottom: 8px; }
  .m-item.mine { justify-content: flex-end; }
  .bubble {
    max-width: 80%; padding: 9px 13px; border-radius: 12px; font-size: 12.5px;
    background: var(--mock-bubble); color: var(--text);
  }
  .m-item.mine .bubble { background: var(--accent); color: #fff; border-radius: 12px 12px 3px 12px; }
  .m-item.theirs .bubble { border-radius: 12px 12px 12px 3px; }
  .bubble small { display: block; font-size: 10.5px; opacity: .65; margin-top: 3px; }
  .mock-toolbar { display: flex; align-items: center; gap: 8px; padding: 11px 14px; background: var(--mock-bar); border-top: 1px solid var(--border); }
  .mbtn { font-size: 11px; padding: 5px 12px; border-radius: 7px; background: var(--mock-bubble); color: var(--text-dim); border: 1px solid var(--border); }
  .mbtn.g { background: var(--accent); color: #fff; border-color: transparent; }
  .mlabel { margin-left: auto; font-size: 11px; color: var(--text-dim); }

  /* ============ 卡片 ============ */
  .card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius); padding: 26px;
    transition: transform .2s, border-color .2s;
  }
  .card:hover { transform: translateY(-4px); border-color: var(--accent); }
  .card .ic {
    width: 46px; height: 46px; border-radius: 12px;
    background: var(--accent-glow); color: var(--accent);
    display: flex; align-items: center; justify-content: center; margin-bottom: 16px;
  }
  .card h3 { font-size: 17px; color: var(--text-bright); margin-bottom: 8px; }
  .card p { color: var(--text-dim); font-size: 14px; }
  .feat-card .eq { display: flex; align-items: center; gap: 8px; margin-top: 10px; }
  .chip { font-size: 11px; color: var(--accent); background: var(--accent-glow); border-radius: 6px; padding: 2px 8px; }

  /* ============ Tab 导出 ============ */
  .tabbar { display: flex; gap: 10px; justify-content: center; margin-bottom: 34px; flex-wrap: wrap; }
  .tabbtn {
    background: var(--bg-card); border: 1px solid var(--border); color: var(--text-dim);
    padding: 10px 26px; border-radius: 999px; font-size: 14.5px; cursor: pointer; font-weight: 600;
    transition: all .2s;
  }
  .tabbtn.active { background: var(--accent); border-color: var(--accent); color: #fff; }
  .panel { display: none; }
  .panel.active { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 32px; align-items: center; animation: fadein .3s; }
  @media (max-width: 860px) { .panel.active { grid-template-columns: 1fr; } }
  @keyframes fadein { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
  .panel-list { display: flex; flex-direction: column; gap: 14px; }
  .panel-item { display: flex; align-items: flex-start; gap: 14px; }
  .panel-item .no { flex: 0 0 auto; width: 28px; height: 28px; border-radius: 50%; background: var(--accent-glow); color: var(--accent); font-weight: 800; font-size: 13px; display: flex; align-items: center; justify-content: center; }
  .panel-item h4 { font-size: 15.5px; color: var(--text-bright); margin-bottom: 3px; }
  .panel-item p { font-size: 13.5px; color: var(--text-dim); }
  .mock2 { background: var(--mock-win); border: 1px solid var(--border-soft); border-radius: 14px; padding: 18px; }
  .mock2 .row { display: flex; justify-content: space-between; align-items: center; padding: 11px 12px; border-bottom: 1px solid var(--border); }
  .mock2 .row:last-child { border-bottom: none; }
  .mock2 .row .n { font-size: 13px; color: var(--text); }
  .mock2 .row .f { font-size: 11px; color: var(--accent); }
  .mock2 .row .dim { font-size: 12px; color: var(--text-dim); }

  /* ============ 步骤 ============ */
  .step { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 28px; position: relative; }
  .step .num { font-size: 46px; font-weight: 900; background: linear-gradient(135deg, #0084ff, #45bdff); -webkit-background-clip: text; background-clip: text; color: transparent; line-height: 1; }
  .step h3 { font-size: 17px; color: var(--text-bright); margin: 14px 0 8px; }
  .step p { color: var(--text-dim); font-size: 14px; }
  .step .tag { position: absolute; top: 26px; right: 26px; font-size: 11px; color: var(--accent); background: var(--accent-glow); border-radius: 6px; padding: 2px 9px; }

  /* ============ 隐私 ============ */
  .privacy-flex { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; }
  @media (max-width: 860px) { .privacy-flex { grid-template-columns: 1fr; } }
  .privacy-list { display: flex; flex-direction: column; gap: 18px; margin-top: 26px; }
  .p-item { display: flex; gap: 14px; align-items: flex-start; }
  .p-item .ic { flex: 0 0 auto; width: 40px; height: 40px; border-radius: 11px; background: var(--accent-glow); color: var(--accent); display: flex; align-items: center; justify-content: center; }
  .p-item h4 { font-size: 15.5px; color: var(--text-bright); margin-bottom: 3px; }
  .p-item p { font-size: 13.5px; color: var(--text-dim); }
  .shield { display: flex; flex-direction: column; align-items: center; justify-content: center; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 50px; text-align: center; }
  .shield .icon { width: 90px; height: 90px; border-radius: 26px; background: var(--accent-glow); display: flex; align-items: center; justify-content: center; margin-bottom: 20px; }
  .shield h3 { color: var(--text-bright); font-size: 20px; }
  .shield p { color: var(--text-dim); font-size: 14px; margin-top: 8px; }

  /* ============ 下载 ============ */
  .download { text-align: center; }
  .dl-card {
    background: linear-gradient(160deg, rgba(0,132,255,.12), rgba(69,189,255,.05));
    border: 1px solid var(--border-soft); border-radius: 20px;
    padding: 54px 40px; max-width: 680px; margin: 0 auto; position: relative; overflow: hidden;
  }
  .dl-card::before { content: ""; position: absolute; inset: 0; background: radial-gradient(400px 200px at 50% -20%, rgba(0,132,255,.25), transparent 60%); pointer-events: none; }
  .dl-card .os { font-size: 13px; color: var(--text-dim); letter-spacing: 2px; text-transform: uppercase; }
  .dl-card h2 { margin: 10px 0 6px; }
  .dl-card .ver { display: inline-block; font-size: 12.5px; color: var(--accent); background: var(--accent-glow); border-radius: 999px; padding: 4px 14px; margin-bottom: 22px; }
  .dl-card .btn { font-size: 16px; padding: 15px 40px; }
  .dl-card .note { font-size: 12.5px; color: var(--text-dim); margin-top: 16px; }
  .qq-link {
    display: inline-flex; align-items: center; gap: 5px;
    font-family: inherit; font-size: inherit;
    background: none; border: none; cursor: pointer; padding: 0;
    color: var(--accent); font-weight: 700; text-decoration: underline;
    text-underline-offset: 3px;
  }
  .qq-link:hover { color: var(--accent-dim); }
  .qq-link.copied { color: var(--accent-dim); text-decoration: none; }
  .os-tags { display: flex; gap: 8px; justify-content: center; margin-top: 18px; flex-wrap: wrap; }
  .os-tags span { font-size: 11.5px; color: var(--text-dim); background: rgba(255,255,255,.04); border: 1px solid var(--border); border-radius: 6px; padding: 3px 10px; }

  /* ============ FAQ ============ */
  .faq-wrap { max-width: 780px; margin: 0 auto; }
  .faq-item { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); margin-bottom: 12px; overflow: hidden; }
  .faq-q { width: 100%; display: flex; justify-content: space-between; align-items: center; gap: 14px; background: none; border: none; color: var(--text-bright); font-size: 15.5px; font-weight: 600; padding: 18px 22px; cursor: pointer; font-family: inherit; text-align: left; }
  .faq-q .arrow { color: var(--accent); transition: transform .25s; flex: 0 0 auto; }
  .faq-item.open .arrow { transform: rotate(45deg); }
  .faq-a { max-height: 0; overflow: hidden; transition: max-height .3s; }
  .faq-a p { padding: 0 22px 18px; color: var(--text-dim); font-size: 14px; }

  /* ============ 警告 ============ */
  .notice {
    background: var(--warn-bg); border: 1px solid var(--warn-bd); color: #fbbf24;
    border-radius: var(--radius-sm); padding: 16px 20px; font-size: 13.5px;
    max-width: 780px; margin: 0 auto;
  }

  /* ============ Footer ============ */
  footer { border-top: 1px solid var(--border); padding: 40px 0 34px; text-align: center; }
  .foot-logo { display: inline-flex; align-items: center; gap: 9px; font-weight: 800; color: var(--text-bright); margin-bottom: 12px; }
  footer .links { display: flex; gap: 22px; justify-content: center; flex-wrap: wrap; margin-bottom: 14px; }
  footer .links a { color: var(--text-dim); font-size: 13.5px; }
  footer .links a:hover { color: var(--accent); }
  footer .copy { color: #6b7280; font-size: 12.5px; }

  /* ============ 内页 · 面包屑 ============ */
  .breadcrumb { font-size: 13px; color: var(--text-dim); padding: 24px 0 0; }
  .breadcrumb ol { list-style: none; display: flex; gap: 8px; flex-wrap: wrap; margin: 0; padding: 0; }
  .breadcrumb li + li::before { content: "/"; margin-right: 8px; color: var(--border-soft); }
  .breadcrumb a { color: var(--text-dim); transition: color .15s; }
  .breadcrumb a:hover { color: var(--accent); }
  .breadcrumb [aria-current] { color: var(--text-bright); }

  /* ============ 内页 · 页头 ============ */
  .page-hero { padding: 56px 0 40px; position: relative; overflow: hidden; }
  .page-hero::before {
    content: ""; position: absolute; inset: 0; pointer-events: none;
    background: radial-gradient(620px 320px at 72% -20%, rgba(0,132,255,.14), transparent 62%);
  }
  .page-hero .container { position: relative; }
  .page-hero h1 { font-size: 36px; font-weight: 900; color: var(--text-bright); line-height: 1.3; letter-spacing: .5px; }
  .page-hero h1 em { font-style: normal; background: linear-gradient(90deg, #45bdff, #0084ff); -webkit-background-clip: text; background-clip: text; color: transparent; }
  .page-hero .p-sub { color: var(--text-dim); font-size: 16px; margin-top: 14px; max-width: 680px; }
  .article-meta { font-size: 13px; color: var(--text-dim); margin-top: 16px; }
  .article-meta time { color: var(--accent); }

  /* ============ 内页 · 正文 ============ */
  .prose { max-width: 800px; margin: 0 auto; }
  .prose h2 { font-size: 25px; margin: 46px 0 14px; letter-spacing: .3px; }
  .prose h3 { font-size: 18px; color: var(--text-bright); margin: 30px 0 10px; }
  .prose p { font-size: 15.5px; margin-bottom: 14px; }
  .prose ul, .prose ol { margin: 0 0 16px 22px; font-size: 15.5px; }
  .prose li { margin-bottom: 8px; }
  .prose strong { color: var(--text-bright); }
  .prose a { color: var(--accent); }
  .prose a:hover { text-decoration: underline; text-underline-offset: 3px; }
  .prose table { width: 100%; border-collapse: collapse; margin: 18px 0 22px; font-size: 14px; }
  .prose th, .prose td { border: 1px solid var(--border); padding: 10px 14px; text-align: left; }
  .prose th { background: var(--bg-card); color: var(--text-bright); }
  .prose td { color: var(--text-dim); }
  .prose .notice { margin: 20px 0; max-width: none; }

  /* ============ 内页 · CTA 与相关阅读 ============ */
  .cta-band {
    background: linear-gradient(160deg, rgba(0,132,255,.12), rgba(69,189,255,.05));
    border: 1px solid var(--border-soft); border-radius: 18px;
    padding: 40px 36px; text-align: center; margin: 52px 0 0;
  }
  .cta-band h2 { font-size: 24px; }
  .cta-band p { color: var(--text-dim); font-size: 14.5px; margin: 10px 0 22px; }
  .rel-links { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; max-width: 900px; margin: 44px auto 0; }
  @media (max-width: 860px) { .rel-links { grid-template-columns: 1fr; } }
  .rel-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 20px 22px; transition: border-color .2s, transform .2s; display: block; }
  .rel-card:hover { border-color: var(--accent); transform: translateY(-3px); }
  .rel-card h3 { font-size: 15.5px; color: var(--text-bright); margin-bottom: 6px; }
  .rel-card p { font-size: 13px; color: var(--text-dim); }
  .rel-card .more { font-size: 12.5px; color: var(--accent); margin-top: 8px; display: inline-block; }

  /* ============ 内页 · 步骤条 ============ */
  .howto { max-width: 800px; margin: 0 auto; }
  .howto-step { display: flex; gap: 16px; align-items: flex-start; padding: 18px 0; border-bottom: 1px dashed var(--border-soft); }
  .howto-step:last-child { border-bottom: none; }
  .howto-step .no { flex: 0 0 auto; width: 34px; height: 34px; border-radius: 50%; background: var(--accent-glow); color: var(--accent); font-weight: 800; font-size: 15px; display: flex; align-items: center; justify-content: center; }
  .howto-step h3 { margin: 4px 0 6px; font-size: 16.5px; color: var(--text-bright); }
  .howto-step p { font-size: 14.5px; color: var(--text-dim); }

  /* ============ 导航当前页高亮 ============ */
  .nav-links a[aria-current="page"] { color: var(--accent); font-weight: 700; }

  /* ============ 文章配图 ============ */
  .prose figure { margin: 22px 0 26px; text-align: center; }
  .prose figure img {
    max-width: 100%; border-radius: 12px;
    border: 1px solid var(--border); box-shadow: var(--shadow-c);
  }
  .prose figcaption { font-size: 12.5px; color: var(--text-dim); margin-top: 10px; }

  /* ============ 英文标语 ============ */
  .hero-en {
    font-size: 14px; letter-spacing: 1.2px; font-weight: 600;
    color: var(--accent); text-transform: uppercase; margin-top: 10px;
  }
  .hero-en span { color: var(--text-dim); font-weight: 400; text-transform: none; letter-spacing: .5px; }

  /* ============ 移动端汉堡菜单 ============ */
  .menu-btn {
    display: none; width: 38px; height: 38px; border-radius: 10px;
    border: 1px solid var(--border-soft); background: var(--bg-card);
    color: var(--text); cursor: pointer; align-items: center; justify-content: center;
    transition: color .2s, border-color .2s;
  }
  .menu-btn:hover { color: var(--accent); border-color: var(--accent); }
  .menu-btn svg { width: 20px; height: 20px; }
  @media (max-width: 760px) {
    .menu-btn { display: flex; }
    .nav { position: relative; }
    .nav-links {
      position: absolute; top: 66px; left: -24px; right: -24px;
      flex-direction: column; gap: 0;
      background: var(--header-bg); backdrop-filter: blur(14px);
      border-bottom: 1px solid var(--border);
      padding: 6px 24px 12px; display: none;
      box-shadow: 0 16px 32px rgba(0,0,0,.18);
    }
    header.nav-open .nav-links { display: flex; }
    .nav-links a { padding: 12px 4px; font-size: 15px; border-bottom: 1px dashed var(--border-soft); }
    .nav-links a:last-child { border-bottom: none; }
  }

  /* ============ 滚动渐入 ============ */
  .rv { opacity: 0; transform: translateY(18px); transition: opacity .6s ease, transform .6s ease; }
  .rv.in { opacity: 1; transform: none; }

  /* ============ 焦点可见性（键盘可访问） ============ */
  a:focus-visible, .btn:focus-visible, .tabbtn:focus-visible, .faq-q:focus-visible,
  .theme-btn:focus-visible, .menu-btn:focus-visible, .qq-link:focus-visible {
    outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 4px;
  }

  /* ============ 浅色主题下的 os-tags 修正 ============ */
  .os-tags span { background: var(--accent-glow); }

  /* ============ Hero mockup 轻浮动 ============ */
  @keyframes floaty { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-10px); } }
  .mock-wrap { animation: floaty 6.5s ease-in-out infinite; }

  /* ============ 减少动态效果偏好 ============ */
  @media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after { animation: none !important; transition: none !important; }
    .rv { opacity: 1; transform: none; }
  }

  /* ============ 移动端排版优化 ============ */
  @media (max-width: 860px) {
    .mock { transform: none; }
    .mock:hover { transform: none; }
  }
  @media (max-width: 600px) {
    .hero { padding: 56px 0 48px; }
    .hero h1 { font-size: 34px; letter-spacing: .5px; }
    .page-hero h1 { font-size: 28px; }
    h2 { font-size: 26px; }
    section { padding: 64px 0; }
    .dl-card { padding: 40px 22px; }
    .stat-row { grid-template-columns: repeat(2, 1fr); }
    .prose table { display: block; overflow-x: auto; }
    .hero-en { font-size: 12px; letter-spacing: .8px; }
  }

  /* ============ 移动端导航紧凑化（防溢出 + 防字体放大） ============ */
  @media (max-width: 760px) {
    .nav { gap: 10px; }
    .nav-right { flex: 0 0 auto; }
    .nav .btn { padding: 8px 16px; font-size: 13px; white-space: nowrap; flex: 0 0 auto; }
    .nav-logo { font-size: 15.5px; gap: 8px; }
    .nav-logo svg { width: 30px; height: 30px; }
  }
  @media (max-width: 480px) {
    .nav { gap: 8px; }
    .nav-right { gap: 8px; }
    .menu-btn, .theme-btn { width: 34px; height: 34px; border-radius: 9px; }
    .nav-logo { font-size: 14px; }
    .nav-logo svg { width: 28px; height: 28px; }
    .nav .btn { padding: 8px 12px; font-size: 12.5px; }
  }
  @media (max-width: 360px) {
    .nav-logo { font-size: 0; gap: 0; }  /* 极窄屏只保留图标 */
    .nav-logo svg { width: 30px; height: 30px; }
  }

  /* ============ 高级感细节 ============ */

  /* 文字选中色 */
  ::selection { background: rgba(0, 132, 255, .30); color: #fff; }
  html[data-theme="light"] ::selection { color: #fff; }

  /* 自定义滚动条 */
  html { scrollbar-width: thin; scrollbar-color: var(--border-soft) var(--bg); }
  ::-webkit-scrollbar { width: 10px; height: 10px; }
  ::-webkit-scrollbar-track { background: var(--bg); }
  ::-webkit-scrollbar-thumb { background: var(--border-soft); border-radius: 8px; border: 2px solid var(--bg); }
  ::-webkit-scrollbar-thumb:hover { background: var(--accent-dim); }

  /* 卡片：顶部微高光 + 悬停辉光 */
  .card, .step {
    background: linear-gradient(180deg, rgba(255,255,255,.03), transparent 42%), var(--bg-card);
  }
  .card:hover, .step:hover {
    border-color: rgba(0, 132, 255, .45);
    box-shadow: 0 14px 36px rgba(0, 132, 255, .13);
  }

  /* 按钮：悬停流光扫过 */
  .btn { position: relative; overflow: hidden; }
  .btn::after {
    content: ""; position: absolute; top: 0; left: -130%; width: 55%; height: 100%;
    background: linear-gradient(100deg, transparent, rgba(255,255,255,.4), transparent);
    transform: skewX(-20deg); transition: left .55s ease; pointer-events: none;
  }
  .btn:hover::after { left: 150%; }

  /* 区块标题：渐变短线点缀 */
  .section-head h2 { position: relative; padding-bottom: 16px; }
  .section-head h2::after {
    content: ""; position: absolute; left: 50%; bottom: 0; transform: translateX(-50%);
    width: 46px; height: 3px; border-radius: 2px;
    background: linear-gradient(90deg, #45bdff, #0084ff);
  }

  /* eyebrow 徽章：内描边更精致 */
  .eyebrow { box-shadow: inset 0 0 0 1px rgba(0, 132, 255, .20); }

  /* 数字用等宽数字，避免跳动 */
  .stat-num, .step .num, .mock2 .row .n { font-variant-numeric: tabular-nums; }

  /* Hero 极光光斑（缓慢漂移，reduced-motion 自动豁免） */
  .hero::after {
    content: ""; position: absolute; width: 540px; height: 540px;
    right: -140px; top: -180px; border-radius: 50%; pointer-events: none;
    background: radial-gradient(circle, rgba(0, 132, 255, .16), transparent 64%);
    filter: blur(12px);
    animation: aurora 16s ease-in-out infinite alternate;
  }
  @keyframes aurora {
    from { transform: translate(0, 0) scale(1); opacity: .85; }
    to   { transform: translate(-70px, 46px) scale(1.18); opacity: 1; }
  }

  /* 下载卡：呼吸光晕 */
  .dl-card::after {
    content: ""; position: absolute; inset: -1px; border-radius: 21px; pointer-events: none;
    box-shadow: 0 0 0 0 rgba(0, 132, 255, 0);
    animation: dlglow 4.5s ease-in-out infinite;
  }
  @keyframes dlglow {
    0%, 100% { box-shadow: 0 0 0 0 rgba(0, 132, 255, 0), 0 0 42px rgba(0, 132, 255, .10); }
    50%      { box-shadow: 0 0 0 0 rgba(0, 132, 255, 0), 0 0 64px rgba(0, 132, 255, .20); }
  }