* { box-sizing: border-box; }
  /* 图片兜底：任何情况下都不会撑破布局 */
  img, svg, video { max-width: 100%; height: auto; }

  /* ================= 功能演示（动图） ================= */
  .demo-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 22px; }
  @media (max-width: 1080px) { .demo-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
  @media (max-width: 720px) { .demo-grid { grid-template-columns: 1fr; } }
  .demo-card {
    background: var(--card); border: 1px solid var(--line); border-radius: 16px;
    padding: 16px; display: flex; flex-direction: column; gap: 10px;
  }
  .demo-card h3 { margin: 2px 0 0; font-size: 17px; color: var(--heading); }
  .demo-sub { margin: 0; color: var(--muted); font-size: 13.5px; }
  .demo-thumb {
    position: relative; border-radius: 12px; overflow: hidden;
    border: 1px solid var(--line); background: #0d1424;
  }
  .demo-thumb img { display: block; width: 100%; height: auto; }
  .demo-play {
    position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%);
    border: 0; cursor: pointer; padding: 10px 18px; border-radius: 999px;
    font-size: 14px; color: #fff; background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    box-shadow: 0 10px 26px rgba(0, 0, 0, 0.45); white-space: nowrap;
  }
  .demo-play:hover { filter: brightness(1.08); }
  .demo-list { margin: 0; padding-left: 18px; color: var(--muted); font-size: 13px; line-height: 1.85; }
  .demo-links { display: flex; gap: 10px; flex-wrap: wrap; margin-top: auto; padding-top: 4px; }
  .demo-play-link {
    border: 1px solid var(--line); background: transparent; color: var(--text);
    border-radius: 9px; padding: 7px 12px; font-size: 12.5px; cursor: pointer;
  }
  .demo-play-link:hover { border-color: var(--accent); color: var(--heading); }
      :root {
        --bg: #080d1a;
        --card: rgba(255, 255, 255, 0.035);
        --line: rgba(255, 255, 255, 0.09);
        --text: #e8eeff;
        --muted: #8b99b5;
        --accent: var(--accent);
        --accent2: var(--accent2);
      }
      html { scroll-behavior: smooth; }
      body {
        margin: 0;
        background: var(--bg);
        color: var(--text);
        font-family: -apple-system, 'Segoe UI', 'Microsoft YaHei', sans-serif;
        line-height: 1.65;
      }
      .glow { position: absolute; border-radius: 50%; filter: blur(90px); opacity: 0.55; pointer-events: none; }
      .nav {
        position: sticky; top: 0; z-index: 20;
        display: flex; align-items: center; justify-content: space-between;
        padding: 14px 40px;
        background: var(--nav-bg);
        backdrop-filter: blur(14px);
        border-bottom: 1px solid var(--line);
      }
      .logo { display: flex; align-items: center; gap: 10px; font-weight: 600; letter-spacing: 0.5px; }
      .logo i {
        width: 30px; height: 30px; border-radius: 9px; display: block;
        background: linear-gradient(140deg, var(--accent), var(--accent2));
        box-shadow: 0 6px 18px color-mix(in srgb, var(--accent) 45%, transparent);
      }
      .nav-links { display: flex; gap: 28px; font-size: 14px; color: var(--muted); }
      .nav-links a { color: inherit; text-decoration: none; }
      .nav-links a:hover { color: var(--heading); }
      .btn {
        display: inline-flex; align-items: center; gap: 8px;
        padding: 11px 22px; border-radius: 10px; font-size: 14px;
        text-decoration: none; border: 1px solid transparent; cursor: pointer;
      }
      .btn-primary {
        background: linear-gradient(135deg, var(--accent), var(--accent-dark)); color: #fff;
        box-shadow: 0 10px 26px color-mix(in srgb, var(--accent) 35%, transparent);
      }
      .btn-ghost { border-color: var(--line); color: var(--text); background: var(--chip-bg); }
      .btn-sm { padding: 8px 16px; font-size: 13px; border-radius: 9px; }

      .wrap { max-width: 1180px; margin: 0 auto; padding: 0 40px; position: relative; z-index: 2; }
      .hero { position: relative; overflow: hidden; padding: 84px 0 70px; }
      .hero .glow.a { width: 620px; height: 620px; left: -180px; top: -260px; background: var(--glow-a); }
      .hero .glow.b { width: 520px; height: 520px; right: -140px; top: -180px; background: var(--glow-b); opacity: 0.35; }
      .hero-grid { display: grid; grid-template-columns: 1.05fr 1fr; gap: 56px; align-items: center; }
      .badge {
        display: inline-flex; align-items: center; gap: 8px;
        padding: 6px 14px; border-radius: 999px; font-size: 12.5px; color: #b9c8e6;
        background: color-mix(in srgb, var(--accent) 12%, transparent); border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent);
      }
      h1 { font-size: 46px; line-height: 1.25; margin: 22px 0 18px; letter-spacing: 0.5px; }
      h1 em { font-style: normal; background: linear-gradient(100deg, var(--accent2), var(--accent) 60%); -webkit-background-clip: text; background-clip: text; color: transparent; }
      .lead { color: var(--muted); font-size: 16.5px; max-width: 520px; margin: 0 0 30px; }
      .hero-actions { display: flex; gap: 14px; align-items: center; margin-bottom: 26px; }
      .hero-meta { display: flex; gap: 26px; color: var(--muted); font-size: 13px; }
      .hero-meta b { color: var(--text); font-weight: 600; }

      /* 客户端窗口示意 */
      .win {
        border-radius: 14px; background: #0f1526; border: 1px solid var(--line);
        box-shadow: 0 40px 90px rgba(0, 0, 0, 0.6); overflow: hidden;
      }
      .win-bar { height: 36px; display: flex; align-items: center; gap: 7px; padding: 0 14px; background: var(--surface); border-bottom: 1px solid var(--line); }
      .win-bar span { width: 10px; height: 10px; border-radius: 50%; }
      .win-body { display: flex; height: 330px; }
      .win-side { width: 138px; background: var(--surface-2); border-right: 1px solid var(--line); padding: 12px 9px; }
      .win-side .brand { color: #dbe4ff; font-size: 12.5px; font-weight: 600; padding: 4px 9px 12px; }
      .win-menu { font-size: 11.5px; color: var(--muted); padding: 8px 10px; border-radius: 7px; margin-bottom: 3px; }
      .win-menu.on { background: linear-gradient(90deg, var(--accent-dark), var(--accent)); color: #fff; }
      .win-main { flex: 1; padding: 14px; display: grid; grid-template-columns: 1fr 1fr; grid-auto-rows: min-content; gap: 11px; background: var(--surface-3); }
      .cell { background: #131a2c; border: 1px solid var(--line); border-radius: 10px; padding: 11px 13px; }
      .cell b { font-size: 21px; display: block; }
      .cell span { font-size: 10.5px; color: var(--muted); }
      .cell.wide { grid-column: 1 / -1; }
      .bars { display: flex; align-items: flex-end; gap: 6px; height: 76px; margin-top: 10px; }
      .bars i { flex: 1; border-radius: 4px 4px 0 0; background: linear-gradient(180deg, var(--accent), #24479c); }

      section { padding: 74px 0; }
      .sec-head { text-align: center; margin-bottom: 44px; }
      .sec-head h2 { font-size: 30px; margin: 0 0 10px; }
      .sec-head p { color: var(--muted); margin: 0; font-size: 15px; }
      .grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
      .grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
      .feature {
        background: var(--card); border: 1px solid var(--line); border-radius: 14px;
        padding: 22px 20px; transition: transform 0.18s, border-color 0.18s;
      }
      .feature:hover { transform: translateY(-3px); border-color: color-mix(in srgb, var(--accent) 45%, transparent); }
      .feature .ico {
        width: 38px; height: 38px; border-radius: 11px; margin-bottom: 14px;
        background: color-mix(in srgb, var(--accent) 14%, transparent); border: 1px solid color-mix(in srgb, var(--accent) 32%, transparent);
        display: flex; align-items: center; justify-content: center;
      }
      .feature .ico svg { width: 19px; height: 19px; stroke: #7fb0ff; fill: none; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
      .feature h3 { font-size: 15.5px; margin: 0 0 8px; }
      .feature p { color: var(--muted); font-size: 13px; margin: 0; line-height: 1.7; }

      .band {
        background: linear-gradient(120deg, color-mix(in srgb, var(--accent) 14%, transparent), color-mix(in srgb, var(--accent2) 6%, transparent));
        border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent); border-radius: 18px;
        padding: 40px 44px; display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center;
      }
      .band h3 { font-size: 24px; margin: 0 0 12px; }
      .band p { color: var(--muted); margin: 0 0 18px; font-size: 14.5px; }
      .tags { display: flex; flex-wrap: wrap; gap: 9px; }
      .tag { padding: 6px 13px; border-radius: 8px; font-size: 12.5px; background: var(--chip-bg); border: 1px solid var(--line); color: var(--text-soft); }

      .price-card {
        background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 30px 28px;
      }
      .price-card.hot { border-color: color-mix(in srgb, var(--accent) 55%, transparent); background: linear-gradient(160deg, color-mix(in srgb, var(--accent) 14%, transparent), var(--chip-bg)); }
      .price-card .name { font-size: 15px; color: var(--text-soft); }
      .price-card .num { font-size: 40px; font-weight: 600; margin: 10px 0 4px; }
      .price-card .num small { font-size: 14px; color: var(--muted); font-weight: 400; }
      .price-card ul { list-style: none; padding: 0; margin: 18px 0 22px; color: var(--muted); font-size: 13.5px; }
      .price-card li { padding: 6px 0 6px 22px; position: relative; }
      .price-card li::before { content: '✓'; position: absolute; left: 0; color: var(--accent2); }

      .cta {
        text-align: center; padding: 56px 40px; border-radius: 20px;
        background: linear-gradient(140deg, color-mix(in srgb, var(--accent-dark) 28%, transparent), color-mix(in srgb, var(--accent2) 10%, transparent));
        border: 1px solid color-mix(in srgb, var(--accent) 35%, transparent);
      }
      .cta h2 { font-size: 28px; margin: 0 0 10px; }
      .cta p { color: #b8c6e4; margin: 0 0 24px; font-size: 14.5px; }
      .dl-row { display: flex; gap: 14px; justify-content: center; align-items: center; flex-wrap: wrap; }
      .dl-note { color: var(--muted); font-size: 12.5px; margin-top: 16px; }
      code.link { background: rgba(0, 0, 0, 0.35); border: 1px solid var(--line); padding: 2px 8px; border-radius: 6px; font-size: 12px; color: #9fd0ff; }

      footer { border-top: 1px solid var(--line); padding: 30px 40px; color: #6f7c96; font-size: 13px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 12px; }

      /* ===== 窄屏自适应 ===== */
      @media (max-width: 1080px) {
        .grid-4 { grid-template-columns: repeat(2, 1fr); }
        .hero-grid { grid-template-columns: 1fr; gap: 40px; }
        .band { grid-template-columns: 1fr; }
      }
      @media (max-width: 760px) {
        .wrap { padding: 0 20px; }
        .nav { padding: 12px 20px; }
        .nav-links { display: none; }
        .hero { padding: 48px 0 40px; }
        h1 { font-size: 30px; }
        .lead { font-size: 15px; }
        .grid-4 { grid-template-columns: 1fr; }
        .sec-head h2 { font-size: 23px; }
        .hero-meta { flex-direction: column; gap: 8px; }
        .hero-actions { flex-wrap: wrap; }
        .win-body { height: 250px; }
        .win-side { width: 108px; }
        .win-menu, .win-menu.on { font-size: 10.5px; padding: 6px 8px; }
        .grid-3 { grid-template-columns: 1fr !important; }
        .price-card .num { font-size: 32px; }
        .cta { padding: 40px 22px; }
        section { padding: 52px 0; }
        footer { flex-direction: column; padding: 24px 20px; }
        .band { padding: 30px 22px; }
      }

      /* ===== 功能截图 ===== */
      .shot {
        margin: 0 0 12px; border-radius: 10px; overflow: hidden; border: 1px solid var(--line);
        background: var(--surface); cursor: zoom-in;
      }
      .shot img { display: block; width: 100%; height: 150px; object-fit: cover; object-position: top left; }
      .feature:hover .shot img { filter: brightness(1.06); }

      /* ===== 左下角小猫头：二维码 + 留言 ===== */
      .cat-fab {
        position: fixed; left: 22px; bottom: 22px; z-index: 80; width: 54px; height: 54px;
        border-radius: 50%; border: 1px solid color-mix(in srgb, var(--accent) 50%, transparent); background: var(--surface-2);
        display: flex; align-items: center; justify-content: center; cursor: pointer;
        box-shadow: 0 10px 26px rgba(0,0,0,.45); transition: transform .16s, box-shadow .16s;
      }
      .cat-fab:hover { transform: translateY(-3px) scale(1.04); box-shadow: 0 14px 30px color-mix(in srgb, var(--accent) 35%, transparent); }
      .cat-fab svg { width: 30px; height: 30px; }
      .cat-panel {
        position: fixed; left: 22px; bottom: 88px; z-index: 81; width: 340px; max-width: calc(100vw - 44px);
        background: #0e1626; border: 1px solid var(--line); border-radius: 16px; padding: 18px;
        box-shadow: 0 24px 60px rgba(0,0,0,.6); display: none;
      }
      .cat-panel.open { display: block; animation: pop .16s ease-out; }
      @keyframes pop { from { opacity: 0; transform: translateY(8px) } to { opacity: 1; transform: none } }
      .cat-panel h4 { margin: 0 0 4px; font-size: 15px; }
      .cat-panel .sub { color: var(--muted); font-size: 12.5px; margin-bottom: 14px; line-height: 1.7; }
      .qr-tabs { display: flex; gap: 8px; margin-bottom: 10px; }
      .qr-tab {
        flex: 1; text-align: center; padding: 7px 0; border-radius: 9px; font-size: 13px; cursor: pointer;
        border: 1px solid var(--line); color: var(--text-soft); background: var(--chip-bg);
      }
      .qr-tab.on { border-color: var(--primary); color: #fff; background: color-mix(in srgb, var(--accent) 16%, transparent); }
      .qr-box { text-align: center; margin-bottom: 6px; }
      .qr-box img { width: 200px; height: 200px; object-fit: contain; border-radius: 12px; background: #fff; }
      .qr-tip { color: var(--muted); font-size: 12px; text-align: center; margin-bottom: 14px; }
      .cat-field { margin-bottom: 10px; }
      .cat-field input, .cat-field textarea {
        width: 100%; padding: 9px 11px; border-radius: 9px; border: 1px solid var(--line);
        background: rgba(8,13,26,.7); color: #e6ecf8; font-size: 13px; outline: none; font-family: inherit;
      }
      .cat-field input:focus, .cat-field textarea:focus { border-color: var(--primary); }
      .cat-field textarea { min-height: 76px; resize: vertical; }
      .cat-actions { display: flex; align-items: center; gap: 10px; }
      .cat-msg { font-size: 12.5px; }
      .cat-msg.ok { color: #6ee7a8; }
      .cat-msg.err { color: #ff8a8a; }
      .lightbox {
        position: fixed; inset: 0; z-index: 90; background: var(--overlay); display: none;
        align-items: center; justify-content: center; padding: 30px; cursor: zoom-out;
      }
      .lightbox.open { display: flex; }
      .lightbox img { max-width: 100%; max-height: 100%; border-radius: 12px; box-shadow: 0 30px 80px rgba(0,0,0,.7); }
    
      /* ===== 多页面补充 ===== */
      .nav-links a.on { color: var(--heading); }
      .nav-links a.on::after { width: 100%; }
      .page-head { padding: 56px 0 10px; text-align: center; }
      .page-head h1 { font-size: 34px; margin: 0 0 12px; }
      .page-head p { color: var(--muted); margin: 0 auto; max-width: 720px; font-size: 15px; line-height: 1.8; }
      .group-title { font-size: 18px; font-weight: 600; margin: 34px 0 14px; display: flex; align-items: center; gap: 10px; }
      .group-title::before { content: ''; width: 4px; height: 16px; border-radius: 2px; background: var(--accent); display: inline-block; }
      .module-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 14px; }
      .module-card {
        background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 20px 18px;
        display: block; text-decoration: none; color: inherit; transition: transform .16s, border-color .16s;
      }
      .module-card:hover { transform: translateY(-3px); border-color: color-mix(in srgb, var(--accent) 50%, transparent); }
      .module-card b { display: block; font-size: 15px; margin-bottom: 8px; color: var(--heading); }
      .module-card span { color: var(--muted); font-size: 12.5px; line-height: 1.7; }
      .two-col-block { display: grid; grid-template-columns: 1fr 1fr; gap: 34px; align-items: center; margin-bottom: 30px; }
      .two-col-block .shot-big { border-radius: 14px; overflow: hidden; border: 1px solid var(--line); background: var(--surface); cursor: zoom-in; }
      .two-col-block .shot-big img { display: block; width: 100%; }
      .two-col-block h3 { font-size: 19px; margin: 0 0 10px; }
      .two-col-block p { color: var(--muted); line-height: 1.9; font-size: 14.5px; margin: 0 0 12px; }
      .steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
      .step-card { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 20px; }
      .step-card b { display: block; margin-bottom: 8px; color: var(--heading); }
      .step-card p { color: var(--muted); font-size: 13.5px; line-height: 1.8; margin: 0; }
      .step-num { display: inline-flex; width: 26px; height: 26px; border-radius: 50%; background: color-mix(in srgb, var(--accent) 18%, transparent); color: #8fb8ff; align-items: center; justify-content: center; font-size: 13px; margin-bottom: 10px; }
      .faq { border: 1px solid var(--line); border-radius: 12px; padding: 16px 18px; margin-bottom: 12px; background: var(--card); }
      .faq b { display: block; margin-bottom: 6px; color: var(--heading); font-size: 14.5px; }
      .faq p { margin: 0; color: var(--muted); font-size: 13.5px; line-height: 1.85; }
      @media (max-width: 1100px) { .module-grid { grid-template-columns: repeat(2, 1fr); } .two-col-block { grid-template-columns: 1fr; } .steps { grid-template-columns: 1fr; } }

      /* ==================== 主题调色板 ====================
         通过 <html data-theme="xxx"> 切换，所有颜色都走上面这些变量。 */
      :root,
      html[data-theme="aurora"] {
        --accent-dark: #2f6ae0;
        --heading: #ffffff;
        --text-soft: #c3d2ef;
        --surface: #0b1120;
        --surface-2: #0d1322;
        --surface-3: #0a1020;
        --glow-a: #1e50ff;
        --glow-b: #00b3c8;
        --nav-bg: rgba(8, 13, 26, 0.82);
        --chip-bg: rgba(255, 255, 255, 0.05);
        --overlay: rgba(3, 7, 16, 0.9);
      }
      html[data-theme="violet"] {
        --bg: #0a0618;
        --card: rgba(168, 85, 247, 0.055);
        --line: rgba(168, 85, 247, 0.18);
        --text: #efe9ff;
        --heading: #ffffff;
        --text-soft: #cdbdf5;
        --muted: #9a8ec0;
        --accent: #a855f7;
        --accent-dark: #7c3aed;
        --accent2: #22d3ee;
        --surface: #100b22;
        --surface-2: #150e2c;
        --surface-3: #0d0820;
        --glow-a: #7c3aed;
        --glow-b: #06b6d4;
        --nav-bg: rgba(10, 6, 24, 0.82);
        --chip-bg: rgba(168, 85, 247, 0.1);
        --overlay: rgba(6, 3, 14, 0.9);
      }
      html[data-theme="forest"] {
        --bg: #04120f;
        --card: rgba(16, 185, 129, 0.055);
        --line: rgba(16, 185, 129, 0.18);
        --text: #e6fff6;
        --heading: #ffffff;
        --text-soft: #b6e8d6;
        --muted: #7ea79a;
        --accent: #10b981;
        --accent-dark: #059669;
        --accent2: #38bdf8;
        --surface: #061a17;
        --surface-2: #08211c;
        --surface-3: #051512;
        --glow-a: #059669;
        --glow-b: #0ea5e9;
        --nav-bg: rgba(4, 18, 15, 0.82);
        --chip-bg: rgba(16, 185, 129, 0.1);
        --overlay: rgba(2, 10, 8, 0.9);
      }
      html[data-theme="gold"] {
        --bg: #0b0a08;
        --card: rgba(245, 158, 11, 0.05);
        --line: rgba(245, 158, 11, 0.18);
        --text: #fdf3e3;
        --heading: #ffffff;
        --text-soft: #e6cfa8;
        --muted: #a3906f;
        --accent: #f59e0b;
        --accent-dark: #b45309;
        --accent2: #fcd34d;
        --surface: #14110c;
        --surface-2: #1a160f;
        --surface-3: #100e0a;
        --glow-a: #b45309;
        --glow-b: #f59e0b;
        --nav-bg: rgba(11, 10, 8, 0.84);
        --chip-bg: rgba(245, 158, 11, 0.1);
        --overlay: rgba(6, 5, 4, 0.9);
      }
      html[data-theme="rose"] {
        --bg: #14060c;
        --card: rgba(244, 63, 94, 0.055);
        --line: rgba(244, 63, 94, 0.2);
        --text: #ffe9ee;
        --heading: #ffffff;
        --text-soft: #f3c3cd;
        --muted: #b5858f;
        --accent: #f43f5e;
        --accent-dark: #be123c;
        --accent2: #fb7185;
        --surface: #1c0a12;
        --surface-2: #240d18;
        --surface-3: #170810;
        --glow-a: #be123c;
        --glow-b: #fb7185;
        --nav-bg: rgba(20, 6, 12, 0.84);
        --chip-bg: rgba(244, 63, 94, 0.1);
        --overlay: rgba(10, 3, 6, 0.9);
      }
      /* 晨曦白：白天看着舒服的浅色主题 */
      html[data-theme="light"] {
        --bg: #f4f7fc;
        --card: #ffffff;
        --line: #dde5f2;
        --text: #16233c;
        --heading: #0d1a31;
        --text-soft: #3f5170;
        --muted: #6b7b99;
        --accent: #2563eb;
        --accent-dark: #1d4ed8;
        --accent2: #0ea5e9;
        --surface: #ffffff;
        --surface-2: #eef3fb;
        --surface-3: #ffffff;
        --glow-a: #bfdbfe;
        --glow-b: #bae6fd;
        --nav-bg: rgba(255, 255, 255, 0.86);
        --chip-bg: rgba(37, 99, 235, 0.07);
        --overlay: rgba(15, 23, 42, 0.55);
      }
      html[data-theme="light"] .glow { opacity: 0.55; }
      html[data-theme="light"] .nav { box-shadow: 0 6px 22px rgba(15, 23, 42, 0.06); }
      html[data-theme="light"] .btn-ghost { background: var(--chip-bg); }
      html[data-theme="light"] .win { box-shadow: 0 30px 70px rgba(15, 23, 42, 0.18); }

      /* ==================== 主题选择器 ==================== */
      .theme-pick { position: relative; margin-left: auto; margin-right: 10px; }
      .theme-btn { display: inline-flex; align-items: center; gap: 8px; }
      .theme-dot {
        width: 13px; height: 13px; border-radius: 50%; display: inline-block;
        background: linear-gradient(135deg, var(--accent), var(--accent2));
        box-shadow: 0 0 0 1px var(--line) inset;
      }
      .theme-menu {
        position: absolute; right: 0; top: calc(100% + 8px); min-width: 156px; padding: 6px;
        border-radius: 12px; border: 1px solid var(--line); background: var(--surface-2);
        box-shadow: 0 18px 40px rgba(0, 0, 0, 0.35); display: none; z-index: 60;
      }
      .theme-menu.open { display: block; }
      .theme-item {
        display: flex; align-items: center; gap: 9px; width: 100%; padding: 8px 10px;
        border: 0; border-radius: 8px; background: transparent; color: var(--text);
        font-size: 13px; text-align: left; cursor: pointer;
      }
      .theme-item:hover { background: var(--chip-bg); }
      .theme-item.on { background: color-mix(in srgb, var(--accent) 18%, transparent); color: var(--heading); }
      .theme-swatch { width: 16px; height: 16px; border-radius: 5px; display: inline-block; flex: 0 0 auto; }
      @media (max-width: 900px) {
        .theme-btn #theme-label { display: none; }
      }

      /* 浅色主题下：首页那个"应用窗口示意图"保持深色（相当于一张深色软件截图），
         否则白底白字看不清 */
      html[data-theme="light"] .win {
        --surface: #0b1120;
        --surface-2: #0d1322;
        --surface-3: #0a1020;
        --text: #e8eeff;
        --muted: #8b99b5;
        --line: rgba(255, 255, 255, 0.09);
        background: var(--surface);
      }
      html[data-theme="light"] .win-side .brand { color: #dbe4ff; }
      html[data-theme="light"] .cell { background: #131a2c; }
      html[data-theme="light"] .cell b { color: #e8eeff; }
      html[data-theme="light"] .win-menu.on { color: #fff; }

      /* 导航排布：logo | 栏目（与 logo 留出间距）| 主题选择 + 下载按钮 */
      .nav .logo { margin-right: 26px; }
      .nav-links { margin-right: auto; }