:root {
      --bg: #07111B;
      --bg-2: #091827;
      --panel: #0E2030;
      --panel-2: #102638;
      --panel-3: #14314A;
      --line: rgba(172, 214, 232, 0.14);
      --line-2: rgba(56, 224, 178, 0.32);
      --text: #EAF2F8;
      --text-2: #B9C9D5;
      --muted: #8296A8;
      --accent: #38E0B2;
      --accent-2: #79F2D2;
      --blue: #60B8FF;
      --violet: #8CA7FF;
      --warning: #F6C760;
      --danger: #FF6B6B;
      --dark: #041018;
      --radius: 22px;
      --radius-lg: 30px;
      --shadow: 0 28px 70px rgba(0, 0, 0, 0.36);
      --max: 1260px;
    }

    * { box-sizing: border-box; }
    html { scroll-behavior: smooth; }

    body {
      margin: 0;
      color: var(--text);
      background:
        radial-gradient(circle at 16% 4%, rgba(56, 224, 178, 0.13), transparent 28%),
        radial-gradient(circle at 82% 8%, rgba(96, 184, 255, 0.10), transparent 30%),
        radial-gradient(circle at 72% 64%, rgba(140, 167, 255, 0.055), transparent 34%),
        linear-gradient(180deg, #07111B 0%, #07111B 48%, #081621 100%);
      font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", Arial, sans-serif;
      overflow-x: hidden;
    }

    body::before {
      content: "";
      position: fixed;
      inset: 0;
      z-index: -2;
      pointer-events: none;
      background-image:
        linear-gradient(rgba(255,255,255,.024) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,.024) 1px, transparent 1px);
      background-size: 42px 42px;
      mask-image: linear-gradient(to bottom, rgba(0,0,0,.82), rgba(0,0,0,.34), transparent 86%);
    }

    a { color: inherit; text-decoration: none; }
    button { font: inherit; }

    .container {
      width: min(var(--max), calc(100% - 44px));
      margin: 0 auto;
    }

    .header {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(7, 17, 27, .78);
      border-bottom: 1px solid rgba(255,255,255,.07);
      backdrop-filter: blur(18px);
    }

    .nav {
      height: 72px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 28px;
    }

    .brand {
      display: inline-flex;
      align-items: center;
      gap: 12px;
      min-width: max-content;
    }

    .brand-mark {
      width: 36px;
      height: 36px;
      border-radius: 12px;
      display: grid;
      place-items: center;
      color: #03130F;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
      box-shadow: 0 0 32px rgba(56, 224, 178, .22);
      font-size: 20px;
      font-weight: 950;
      letter-spacing: -.06em;
    }

    .brand-text strong {
      display: block;
      font-size: 16px;
      line-height: 1;
      letter-spacing: .13em;
    }

    .brand-text span {
      display: block;
      margin-top: 5px;
      color: var(--muted);
      font-size: 11px;
      letter-spacing: .12em;
      text-transform: uppercase;
    }

    .nav-actions {
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .btn {
      min-height: 42px;
      padding: 11px 18px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 9px;
      border-radius: 999px;
      border: 1px solid transparent;
      cursor: pointer;
      font-size: 14px;
      font-weight: 780;
      white-space: nowrap;
      transition: transform .22s ease, background .22s ease, border-color .22s ease, box-shadow .22s ease;
    }

    .btn:hover { transform: translateY(-2px); }

    .btn svg {
      width: 17px;
      height: 17px;
      flex: 0 0 auto;
    }

    .btn-primary {
      color: #03130F;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
      box-shadow: 0 14px 36px rgba(56, 224, 178, .18);
    }

    .btn-secondary {
      color: var(--text);
      background: rgba(255,255,255,.055);
      border-color: rgba(255,255,255,.12);
    }

    .btn-ghost {
      color: var(--text-2);
      background: rgba(255,255,255,.04);
      border-color: rgba(255,255,255,.11);
    }

    .mobile-toggle,
    .mobile-menu { display: none; }

    .hero {
      padding: 78px 0 18px;
    }

    .hero-grid {
      display: grid;
      grid-template-columns: 1fr;
      align-items: center;
      gap: 54px;
    }

    .back-link {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      color: #BFF9E7;
      height: 32px;
      padding: 0 12px;
      border-radius: 999px;
      background: rgba(56,224,178,.07);
      border: 1px solid rgba(56,224,178,.15);
      font-size: 13px;
      font-weight: 760;
    }

    .hero h1 {
      margin: 20px 0 0;
      font-size: clamp(40px, 4.8vw, 64px);
      line-height: 1.05;
      letter-spacing: -0.06em;
      font-weight: 920;
    }

    .hero p {
      max-width: 650px;
      margin: 20px 0 0;
      color: var(--text-2);
      font-size: 16px;
      line-height: 1.84;
    }

    .hero-panel {
      display: none;
      padding: 24px;
      border-radius: var(--radius-lg);
      background:
        radial-gradient(circle at 18% 8%, rgba(56,224,178,.12), transparent 32%),
        linear-gradient(180deg, rgba(14,32,48,.88), rgba(10,24,38,.78));
      border: 1px solid var(--line);
      box-shadow: var(--shadow);
    }

    .hero-panel-row {
      display: grid;
      grid-template-columns: 46px 1fr;
      gap: 14px;
      align-items: start;
      min-height: 74px;
      padding: 14px 0;
      border-bottom: 1px solid rgba(255,255,255,.075);
    }

    .hero-panel-row:last-child { border-bottom: 0; }

    .hero-panel-icon {
      width: 46px;
      height: 46px;
      border-radius: 16px;
      display: grid;
      place-items: center;
      color: #03130F;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
      font-size: 18px;
      font-weight: 900;
    }

    .hero-panel-row strong {
      display: block;
      font-size: 16px;
      color: var(--text);
    }

    .hero-panel-row span {
      display: block;
      margin-top: 6px;
      color: var(--muted);
      font-size: 13px;
      line-height: 1.62;
    }

    .switch-section {
      padding: 22px 0 70px;
    }

    .guide-shell {
      border-radius: 34px;
      background:
        linear-gradient(180deg, rgba(14,32,48,.88), rgba(10,24,38,.78));
      border: 1px solid var(--line);
      box-shadow: 0 28px 70px rgba(0,0,0,.28);
      overflow: hidden;
    }

    .tabbar {
      position: relative;
      z-index: 30;
      display: flex;
      justify-content: space-between;
      align-items: center;
      gap: 14px;
      padding: 16px;
      background: rgba(10,24,38,.88);
      border-bottom: 1px solid rgba(255,255,255,.08);
      backdrop-filter: blur(16px);
    }

    .tabs {
      display: flex;
      gap: 10px;
      flex-wrap: wrap;
    }

    .tab-btn {
      min-height: 46px;
      padding: 0 18px;
      border: 1px solid rgba(255,255,255,.12);
      border-radius: 999px;
      color: var(--text-2);
      background: rgba(255,255,255,.045);
      cursor: pointer;
      font-size: 14px;
      font-weight: 860;
      transition: background .22s ease, border-color .22s ease, color .22s ease, transform .22s ease;
    }

    .tab-btn:hover { transform: translateY(-2px); }

    .tab-btn.active {
      color: #03130F;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
      border-color: rgba(56,224,178,.45);
      box-shadow: 0 14px 34px rgba(56,224,178,.16);
    }

    .tabbar-note {
      display: none;
      color: var(--muted);
      font-size: 13px;
      line-height: 1.5;
    }

    .os-panel { display: none; }
    .os-panel.active { display: block; }
    .os-panel { padding-top: 0; }

    .os-head {
      display: flex;
      align-items: start;
      justify-content: space-between;
      gap: 22px;
      padding: 30px 30px 24px;
      border-bottom: 1px solid rgba(255,255,255,.075);
    }

    .os-title {
      display: flex;
      align-items: start;
      gap: 16px;
    }

    .os-icon {
      flex: 0 0 auto;
      width: 54px;
      height: 54px;
      border-radius: 18px;
      display: grid;
      place-items: center;
      color: #03130F;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
      font-size: 24px;
      font-weight: 950;
    }

    .os-title h2 {
      margin: 0;
      font-size: clamp(30px, 3.6vw, 44px);
      line-height: 1.08;
      letter-spacing: -0.06em;
      font-weight: 900;
    }

    .os-title p {
      max-width: 760px;
      margin: 10px 0 0;
      color: var(--text-2);
      font-size: 14px;
      line-height: 1.72;
    }

    .os-badge {
      flex: 0 0 auto;
      min-height: 32px;
      padding: 0 12px;
      display: inline-flex;
      align-items: center;
      border-radius: 999px;
      color: #BFF9E7;
      background: rgba(56,224,178,.08);
      border: 1px solid rgba(56,224,178,.16);
      font-size: 12px;
      font-weight: 840;
      white-space: nowrap;
    }

    .steps {
      display: grid;
      gap: 24px;
      padding: 24px;
    }

    .lesson {
      border-radius: 28px;
      background: rgba(255,255,255,.038);
      border: 1px solid rgba(255,255,255,.075);
      overflow: hidden;
    }

    .lesson-top {
      display: flex;
      align-items: flex-start;
      justify-content: space-between;
      gap: 22px;
      padding: 24px 24px 18px;
      border-bottom: 1px solid rgba(255,255,255,.065);
    }

    .lesson-title {
      display: flex;
      align-items: flex-start;
      gap: 14px;
    }

    .lesson-num {
      flex: 0 0 auto;
      width: 44px;
      height: 44px;
      display: grid;
      place-items: center;
      border-radius: 15px;
      color: #03130F;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
      font-size: 15px;
      font-weight: 920;
    }

    .lesson-title h3 {
      margin: 0;
      font-size: 24px;
      line-height: 1.22;
      letter-spacing: -0.045em;
      font-weight: 880;
    }

    .lesson-title p {
      max-width: 820px;
      margin: 8px 0 0;
      color: var(--text-2);
      font-size: 14px;
      line-height: 1.74;
    }

    .lesson-tag {
      flex: 0 0 auto;
      min-height: 30px;
      padding: 0 11px;
      display: inline-flex;
      align-items: center;
      border-radius: 999px;
      color: #CFE8FF;
      background: rgba(96,184,255,.08);
      border: 1px solid rgba(96,184,255,.18);
      font-size: 12px;
      font-weight: 840;
      white-space: nowrap;
    }

    .lesson-body {
      display: grid;
      grid-template-columns: minmax(320px, .72fr) minmax(600px, 1.28fr);
      gap: 24px;
      align-items: start;
      padding: 24px;
    }

    .text-blocks {
      display: grid;
      gap: 14px;
    }

    .text-panel {
      padding: 17px 17px 15px;
      border-radius: 19px;
      background: rgba(255,255,255,.032);
      border: 1px solid rgba(255,255,255,.075);
    }

    .text-panel strong {
      display: block;
      color: var(--text);
      font-size: 14px;
      margin-bottom: 10px;
    }

    .text-panel p {
      margin: 0;
      color: var(--muted);
      font-size: 13px;
      line-height: 1.7;
    }

    .task-list {
      margin: 0;
      padding: 0;
      list-style: none;
      display: grid;
      gap: 9px;
    }

    .task-list li {
      position: relative;
      padding-left: 19px;
      color: var(--text-2);
      font-size: 13px;
      line-height: 1.7;
    }

    .task-list li::before {
      content: "";
      position: absolute;
      left: 0;
      top: .62em;
      width: 6px;
      height: 6px;
      border-radius: 999px;
      background: var(--accent);
    }

    .task-list.warning li::before { background: var(--warning); }

    .hi {
      color: #BFF9E7;
      font-weight: 760;
    }

    .visual-card {
      width: 100%;
      min-width: 0;
      padding: 12px;
      border-radius: 26px;
      background: linear-gradient(180deg, rgba(255,255,255,.12), rgba(255,255,255,.035));
      border: 1px solid rgba(255,255,255,.10);
      box-shadow: 0 26px 60px rgba(0,0,0,.22);
    }

    .visual-caption {
      display: none;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 14px;
      margin: 0 0 10px;
      color: var(--muted);
      font-size: 12px;
      line-height: 1.5;
    }

    .visual-caption b {
      color: var(--text-2);
      font-weight: 820;
    }

    .browser-frame,
    .system-frame,
    .mac-frame {
      overflow: hidden;
      border-radius: 18px;
      border: 1px solid rgba(255,255,255,.08);
      background: #0B1825;
      min-height: 460px;
    }

    .window-bar {
      height: 42px;
      display: flex;
      align-items: center;
      gap: 11px;
      padding: 0 14px;
      background: rgba(255,255,255,.055);
      border-bottom: 1px solid rgba(255,255,255,.07);
    }

    .win-dots,
    .mac-dots {
      display: flex;
      gap: 6px;
      flex: 0 0 auto;
    }

    .win-dots i {
      width: 9px;
      height: 9px;
      border-radius: 2px;
      background: rgba(255,255,255,.26);
      display: block;
    }

    .mac-dots i {
      width: 11px;
      height: 11px;
      border-radius: 999px;
      display: block;
    }

    .mac-dots i:nth-child(1) { background: #FF5F57; }
    .mac-dots i:nth-child(2) { background: #FEBC2E; }
    .mac-dots i:nth-child(3) { background: #28C840; }

    .bar-name {
      flex: 1;
      color: var(--muted);
      font-size: 12px;
      text-align: center;
    }

    .frame-body { padding: 24px; }

    .browser-frame.light,
    .system-frame.light,
    .mac-frame.light {
      background: #F3F6FA;
      color: #162033;
    }

    .browser-frame.light .window-bar,
    .system-frame.light .window-bar,
    .mac-frame.light .window-bar {
      background: #E8EEF5;
      border-bottom-color: #D6E0EB;
    }

    .browser-frame.light .bar-name,
    .system-frame.light .bar-name,
    .mac-frame.light .bar-name { color: #6B778C; }

    .browser-address {
      width: 100%;
      height: 34px;
      display: flex;
      align-items: center;
      gap: 8px;
      padding: 0 13px;
      border-radius: 999px;
      background: rgba(255,255,255,.075);
      color: var(--muted);
      font-size: 12px;
    }

    .light .browser-address {
      background: #FFFFFF;
      border: 1px solid #D8E3EE;
      color: #667085;
    }

    .site-screen {
      margin-top: 20px;
      padding: 24px;
      border-radius: 20px;
      background:
        radial-gradient(circle at 16% 10%, rgba(56,224,178,.16), transparent 32%),
        rgba(255,255,255,.045);
      border: 1px solid rgba(255,255,255,.08);
    }

    .light .site-screen {
      background: #FFFFFF;
      border-color: #E2EAF3;
    }

    .mini-nav {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 14px;
      padding-bottom: 18px;
      border-bottom: 1px solid rgba(255,255,255,.075);
    }

    .light .mini-nav { border-bottom-color: #E8EEF5; }

    .mini-logo {
      display: inline-flex;
      align-items: center;
      gap: 10px;
      font-weight: 860;
      color: var(--text);
    }

    .light .mini-logo { color: #162033; }

    .logo-box {
      width: 30px;
      height: 30px;
      border-radius: 10px;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
    }

    .mini-links {
      display: flex;
      gap: 18px;
      color: var(--muted);
      font-size: 12px;
    }

    .download-hero {
      padding: 34px 0 10px;
      text-align: center;
    }

    .download-hero h4 {
      margin: 0 0 10px;
      font-size: 30px;
      color: var(--text);
      letter-spacing: -.04em;
    }

    .light .download-hero h4 { color: #162033; }

    .download-hero p {
      margin: 0;
      color: var(--muted);
      font-size: 14px;
    }

    .green-download {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      min-height: 48px;
      margin-top: 22px;
      padding: 0 22px;
      border-radius: 14px;
      color: #03130F;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
      font-size: 14px;
      font-weight: 900;
      box-shadow: 0 14px 36px rgba(56,224,178,.17);
    }

    .file-row {
      margin-top: 24px;
      padding-top: 16px;
      border-top: 1px solid rgba(255,255,255,.075);
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 16px;
      color: var(--muted);
      font-size: 12px;
    }

    .light .file-row { border-top-color: #E8EEF5; }

    .file-row b { color: var(--text-2); }
    .light .file-row b { color: #162033; }

    .download-warning-layout {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 18px;
    }

    .download-popover {
      border-radius: 16px;
      background: #FFFFFF;
      border: 1px solid #DCE5EF;
      box-shadow: 0 20px 46px rgba(13, 32, 52, .18);
      overflow: hidden;
      min-height: 330px;
      color: #1F2937;
    }

    .popover-top {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 50px;
      padding: 0 16px;
      border-bottom: 1px solid #EDF1F6;
      font-weight: 760;
      color: #101828;
    }

    .popover-icons {
      display: flex;
      gap: 12px;
      color: #8A94A6;
      font-size: 14px;
    }

    .file-alert {
      margin: 16px;
      padding: 14px;
      border-radius: 12px;
      background: #FFF7ED;
      border: 1px solid #FED7AA;
      color: #7C4A03;
      font-size: 13px;
      line-height: 1.58;
    }

    .file-alert strong {
      display: block;
      margin-bottom: 6px;
      color: #5E3B00;
    }

    .file-alert .filename {
      color: #111827;
      font-weight: 760;
    }

    .alert-actions {
      display: flex;
      justify-content: flex-end;
      gap: 9px;
      margin: 14px 16px 0;
    }

    .ui-btn {
      min-height: 34px;
      padding: 0 13px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      border-radius: 8px;
      border: 1px solid #D0DAE5;
      background: #F8FAFC;
      color: #344054;
      font-size: 12px;
      font-weight: 760;
      white-space: nowrap;
    }

    .ui-btn.danger-outline,
    .focus-ring {
      border-color: #FF6B6B !important;
      box-shadow:
        0 0 0 2px rgba(255,107,107,.14) inset,
        0 0 0 2px rgba(255,107,107,.06);
    }

    .sub-menu {
      margin: 14px 16px 16px auto;
      width: 180px;
      padding: 8px;
      border-radius: 12px;
      background: #FFFFFF;
      border: 1px solid #DCE5EF;
      box-shadow: 0 18px 38px rgba(13, 32, 52, .16);
    }

    .sub-menu span {
      display: block;
      padding: 10px 11px;
      border-radius: 9px;
      color: #344054;
      font-size: 12px;
      font-weight: 700;
    }

    .sub-menu .focus-ring { color: #111827; }

    .smart-wrap {
      width: min(610px, 100%);
      margin: 10px auto;
      border-radius: 0;
      background: linear-gradient(135deg, #0078D7, #0054B8);
      color: #FFFFFF;
      min-height: 365px;
      padding: 34px 34px 28px;
      position: relative;
      box-shadow: 0 24px 54px rgba(0, 92, 200, .24);
    }

    .smart-wrap h4 {
      margin: 0 0 18px;
      font-size: 25px;
      font-weight: 760;
      letter-spacing: -.02em;
    }

    .smart-wrap p {
      max-width: 450px;
      margin: 0;
      color: rgba(255,255,255,.88);
      font-size: 14px;
      line-height: 1.72;
    }

    .more-info {
      display: inline-flex;
      margin-top: 22px;
      color: #FFFFFF;
      font-size: 14px;
      font-weight: 760;
      border-bottom: 2px solid #FFFFFF;
    }

    .smart-meta {
      margin-top: 22px;
      color: rgba(255,255,255,.88);
      font-size: 13px;
      line-height: 1.8;
    }

    .smart-actions {
      position: absolute;
      right: 28px;
      bottom: 26px;
      display: flex;
      gap: 10px;
    }

    .smart-btn {
      min-width: 102px;
      min-height: 36px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      background: #FFFFFF;
      color: #0F172A;
      font-size: 13px;
      font-weight: 760;
    }

    .uac-dialog {
      width: min(620px, 100%);
      margin: 12px auto;
      background: #FFFFFF;
      color: #111827;
      border: 1px solid #CCD7E5;
      box-shadow: 0 26px 58px rgba(13, 32, 52, .18);
    }

    .uac-bar {
      height: 46px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 18px;
      background: #E8F3FF;
      border-bottom: 1px solid #D5E6F7;
      color: #344054;
      font-size: 13px;
      font-weight: 760;
    }

    .uac-body {
      padding: 26px 30px 28px;
    }

    .uac-body h4 {
      margin: 0 0 22px;
      font-size: 23px;
      line-height: 1.35;
      font-weight: 760;
    }

    .uac-app {
      display: grid;
      grid-template-columns: 54px 1fr;
      gap: 14px;
      align-items: center;
      margin-bottom: 18px;
    }

    .uac-icon {
      width: 54px;
      height: 54px;
      border-radius: 14px;
      background: linear-gradient(135deg, var(--accent), var(--blue));
    }

    .uac-app strong {
      display: block;
      margin-bottom: 5px;
      color: #111827;
    }

    .uac-app span,
    .uac-meta {
      color: #667085;
      font-size: 13px;
      line-height: 1.7;
    }

    .uac-actions {
      display: flex;
      justify-content: flex-end;
      gap: 12px;
      margin-top: 26px;
    }

    .uac-actions .ui-btn {
      min-width: 92px;
      min-height: 38px;
    }

    .installer-dialog {
      width: min(660px, 100%);
      margin: 10px auto;
      border-radius: 14px;
      overflow: hidden;
      background: #FFFFFF;
      color: #111827;
      border: 1px solid #D6E0EB;
      box-shadow: 0 26px 58px rgba(13, 32, 52, .18);
    }

    .installer-head {
      padding: 20px 24px;
      border-bottom: 1px solid #E4EBF3;
      display: flex;
      gap: 14px;
      align-items: center;
    }

    .installer-icon {
      width: 48px;
      height: 48px;
      border-radius: 14px;
      background: linear-gradient(135deg, var(--accent), var(--blue));
    }

    .installer-head strong {
      display: block;
      font-size: 18px;
      margin-bottom: 4px;
    }

    .installer-head span {
      color: #667085;
      font-size: 13px;
    }

    .installer-body {
      padding: 28px 24px;
      min-height: 180px;
    }

    .installer-note {
      color: #667085;
      font-size: 13px;
      line-height: 1.7;
      margin: 10px 0 0;
    }

    .progress-track {
      height: 10px;
      border-radius: 999px;
      background: #E6EDF5;
      overflow: hidden;
      margin-top: 22px;
    }

    .progress-fill {
      width: 76%;
      height: 100%;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
    }

    .installer-actions {
      padding: 16px 24px;
      display: flex;
      justify-content: flex-end;
      gap: 10px;
      background: #F8FAFC;
      border-top: 1px solid #E4EBF3;
    }

    .about-window {
      width: min(620px, 100%);
      margin: 10px auto;
      border-radius: 18px;
      overflow: hidden;
      background: #FFFFFF;
      color: #111827;
      border: 1px solid #DCE5EF;
      box-shadow: 0 26px 58px rgba(13, 32, 52, .16);
    }

    .about-body {
      padding: 28px;
      display: grid;
      grid-template-columns: 82px 1fr;
      gap: 18px;
      align-items: start;
    }

    .mac-logo {
      width: 76px;
      height: 76px;
      border-radius: 18px;
      background: linear-gradient(135deg, #DCE7F3, #FFFFFF);
      border: 1px solid #D9E3EE;
      display: grid;
      place-items: center;
      color: #111827;
      font-size: 34px;
      font-weight: 900;
    }

    .about-body h4 {
      margin: 0 0 12px;
      font-size: 22px;
    }

    .about-table {
      display: grid;
      gap: 8px;
      color: #667085;
      font-size: 13px;
      line-height: 1.55;
    }

    .about-table b {
      color: #111827;
    }

    .file-cards {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 14px;
      margin-top: 20px;
    }

    .file-cards-two {
      grid-template-columns: 1fr 1fr;
    }

    .file-card {
      min-height: 132px;
      padding: 16px;
      border-radius: 16px;
      background: #FFFFFF;
      border: 1px solid #DCE5EF;
      color: #111827;
      box-shadow: 0 12px 28px rgba(13, 32, 52, .08);
    }

    .file-card b {
      display: block;
      margin-bottom: 10px;
      font-size: 20px;
    }

    .file-card strong {
      display: block;
      margin-bottom: 6px;
    }

    .file-card span {
      color: #667085;
      font-size: 12px;
      line-height: 1.6;
    }

    .file-name-note {
      margin-top: 16px;
      padding: 14px 16px;
      border-radius: 14px;
      background: #FFFFFF;
      border: 1px solid #DCE5EF;
      color: #667085;
      font-size: 13px;
      line-height: 1.7;
    }

    .file-name-note b {
      color: #111827;
    }

    .dmg-window {
      width: min(680px, 100%);
      margin: 10px auto;
      border-radius: 18px;
      overflow: hidden;
      background: #FFFFFF;
      color: #111827;
      border: 1px solid #DCE5EF;
      box-shadow: 0 26px 58px rgba(13, 32, 52, .16);
    }

    .dmg-body {
      padding: 44px 42px 36px;
      min-height: 330px;
    }

    .drag-row {
      display: grid;
      grid-template-columns: 1fr 96px 1fr;
      gap: 18px;
      align-items: center;
    }

    .drag-item {
      display: grid;
      justify-items: center;
      gap: 13px;
      color: #111827;
      font-size: 14px;
      font-weight: 780;
    }

    .app-icon {
      width: 92px;
      height: 92px;
      border-radius: 26px;
      background: linear-gradient(135deg, var(--accent), var(--blue));
      position: relative;
      box-shadow: 0 18px 32px rgba(13, 32, 52, .16);
    }

    .app-icon::after {
      content: "";
      position: absolute;
      inset: 24px;
      border-radius: 16px;
      background: rgba(255,255,255,.92);
    }

    .folder-icon {
      width: 106px;
      height: 78px;
      border-radius: 18px;
      background: linear-gradient(180deg, #82C4FF, #2F84EE);
      position: relative;
      box-shadow: 0 18px 32px rgba(13, 32, 52, .16);
    }

    .folder-icon::before {
      content: "";
      position: absolute;
      left: 12px;
      top: -10px;
      width: 46px;
      height: 20px;
      border-radius: 9px 9px 0 0;
      background: #A6D7FF;
    }

    .big-arrow {
      text-align: center;
      color: #8AA0B8;
      font-size: 54px;
      font-weight: 300;
    }

    .mac-alert {
      width: min(620px, 100%);
      margin: 70px auto;
      background: #FFFFFF;
      border-radius: 16px;
      color: #111827;
      box-shadow: 0 28px 68px rgba(13, 32, 52, .22);
      border: 1px solid #DCE5EF;
      padding: 24px;
      display: grid;
      grid-template-columns: 58px 1fr;
      gap: 18px;
      align-items: start;
    }

    .alert-icon {
      width: 56px;
      height: 56px;
      border-radius: 16px;
      background: #FFF7ED;
      border: 1px solid #FED7AA;
      color: #F59E0B;
      display: grid;
      place-items: center;
      font-size: 30px;
      font-weight: 900;
    }

    .mac-alert h4 {
      margin: 0 0 10px;
      font-size: 18px;
      line-height: 1.42;
      font-weight: 760;
    }

    .mac-alert p {
      margin: 0;
      color: #667085;
      font-size: 13px;
      line-height: 1.7;
    }

    .mac-alert-actions {
      display: flex;
      justify-content: flex-end;
      gap: 10px;
      margin-top: 20px;
    }

    .settings-window {
      width: min(760px, 100%);
      margin: 10px auto;
      border-radius: 18px;
      overflow: hidden;
      background: #FFFFFF;
      color: #111827;
      border: 1px solid #DCE5EF;
      box-shadow: 0 26px 58px rgba(13, 32, 52, .16);
    }

    .settings-body {
      display: grid;
      grid-template-columns: 210px 1fr;
      min-height: 470px;
    }

    .settings-side {
      padding: 16px 12px;
      background: #F5F8FC;
      border-right: 1px solid #E1E8F0;
    }

    .settings-search {
      height: 32px;
      padding: 0 11px;
      border-radius: 9px;
      background: #EAEFF5;
      color: #8A94A6;
      font-size: 12px;
      display: flex;
      align-items: center;
      margin-bottom: 12px;
    }

    .settings-menu {
      display: grid;
      gap: 3px;
    }

    .settings-menu span {
      min-height: 34px;
      padding: 0 10px;
      border-radius: 9px;
      display: flex;
      align-items: center;
      color: #667085;
      font-size: 13px;
    }

    .settings-menu .active {
      color: #1677FF;
      background: #EAF3FF;
      font-weight: 760;
    }

    .settings-main {
      padding: 24px;
    }

    .settings-main h4 {
      margin: 0 0 22px;
      font-size: 26px;
      letter-spacing: -.04em;
    }

    .security-block {
      padding: 18px;
      border-radius: 16px;
      border: 1px solid #E1E8F0;
      background: #FBFCFE;
    }

    .security-block strong {
      display: block;
      margin-bottom: 10px;
      font-size: 15px;
    }

    .security-block p {
      margin: 0;
      color: #667085;
      font-size: 13px;
      line-height: 1.7;
    }

    .open-anyway-row {
      display: flex;
      justify-content: space-between;
      gap: 16px;
      align-items: center;
      padding-top: 16px;
      margin-top: 16px;
      border-top: 1px solid #E7EDF4;
    }

    .open-anyway-row span {
      color: #667085;
      font-size: 13px;
      line-height: 1.6;
    }

    .open-anyway {
      flex: 0 0 auto;
      min-height: 36px;
      padding: 0 14px;
      border-radius: 9px;
      background: #FFFFFF;
      border: 1px solid #FF6B6B;
      box-shadow:
        0 0 0 2px rgba(255,107,107,.14) inset,
        0 0 0 2px rgba(255,107,107,.06);
      color: #111827;
      font-size: 13px;
      font-weight: 760;
    }

    .final-modal {
      width: min(540px, 100%);
      margin: 18px auto 0;
      padding: 22px;
      border-radius: 16px;
      background: #FFFFFF;
      border: 1px solid #DCE5EF;
      color: #111827;
      box-shadow: 0 20px 46px rgba(13, 32, 52, .14);
    }

    .final-modal h4 {
      margin: 0 0 9px;
      font-size: 18px;
    }

    .final-modal p {
      margin: 0;
      color: #667085;
      font-size: 13px;
      line-height: 1.68;
    }

    .final-modal-actions {
      display: flex;
      justify-content: flex-end;
      gap: 10px;
      margin-top: 18px;
    }

    .safety {
      margin-top: 24px;
      padding: 24px;
      border-radius: 28px;
      background:
        linear-gradient(180deg, rgba(14,32,48,.88), rgba(10,24,38,.78));
      border: 1px solid var(--line);
    }

    .safety h3 {
      margin: 0 0 16px;
      font-size: 26px;
      letter-spacing: -.045em;
      display: flex;
      align-items: center;
      gap: 12px;
    }

    .safety h3 b {
      width: 40px;
      height: 40px;
      display: grid;
      place-items: center;
      color: #03130F;
      border-radius: 14px;
      background: linear-gradient(135deg, var(--accent), var(--accent-2));
    }

    .safety-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px 20px;
      margin: 0;
      padding: 0;
      list-style: none;
    }

    .safety-grid li {
      position: relative;
      padding-left: 18px;
      color: var(--text-2);
      font-size: 14px;
      line-height: 1.72;
    }

    .safety-grid li::before {
      content: "";
      position: absolute;
      left: 0;
      top: .64em;
      width: 6px;
      height: 6px;
      border-radius: 999px;
      background: var(--accent);
    }

    .bottom-help {
      margin-top: 18px;
      padding: 24px 26px;
      border-radius: 28px;
      background:
        radial-gradient(circle at 12% 12%, rgba(56,224,178,.10), transparent 34%),
        linear-gradient(180deg, rgba(14,32,48,.88), rgba(10,24,38,.78));
      border: 1px solid var(--line);
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 22px;
    }

    .bottom-help h3 {
      margin: 0 0 8px;
      font-size: 26px;
      letter-spacing: -.045em;
    }

    .bottom-help p {
      margin: 0;
      color: var(--text-2);
      font-size: 14px;
      line-height: 1.72;
    }

    .bottom-actions {
      display: flex;
      gap: 12px;
      flex-wrap: wrap;
    }

    footer {
      padding: 28px 0;
      color: var(--muted);
      border-top: 1px solid rgba(255,255,255,.075);
      font-size: 13px;
    }

    .footer-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 20px;
      flex-wrap: wrap;
    }

    .reveal {
      opacity: 0;
      transform: translateY(18px);
      transition: opacity .58s ease, transform .58s cubic-bezier(.16,1,.3,1);
    }

    .reveal.visible {
      opacity: 1;
      transform: translateY(0);
    }

    @media (max-width: 1180px) {
      .lesson-body {
        grid-template-columns: 1fr;
      }

      .browser-frame,
      .system-frame,
      .mac-frame {
        min-height: auto;
      }
    }

    @media (max-width: 980px) {
      .hero-grid {
        grid-template-columns: 1fr;
      }

      .download-warning-layout,
      .safety-grid {
        grid-template-columns: 1fr;
      }

      .tabbar {
        align-items: flex-start;
        flex-direction: column;
      }

      .os-head,
      .lesson-top,
      .bottom-help {
        align-items: flex-start;
        flex-direction: column;
      }
    }

    @media (max-width: 860px) {
      .nav-actions .hide-mobile {
        display: none;
      }

      .mobile-toggle {
        display: grid;
        place-items: center;
        width: 42px;
        height: 42px;
        border-radius: 999px;
        color: var(--text);
        background: rgba(255,255,255,.055);
        border: 1px solid rgba(255,255,255,.11);
        cursor: pointer;
      }

      .mobile-menu {
        padding: 0 0 16px;
        border-top: 1px solid rgba(255,255,255,.07);
      }

      .mobile-menu.open {
        display: grid;
        gap: 10px;
      }

      .mobile-menu a {
        padding: 10px 0;
        color: var(--text-2);
      }
    }

    @media (max-width: 680px) {
      .container {
        width: min(var(--max), calc(100% - 28px));
      }

      .brand-text span {
        display: none;
      }

      .btn {
        width: 100%;
      }

      .tabs,
      .tab-btn,
      .bottom-actions {
        width: 100%;
      }

      .tab-btn {
        justify-content: center;
      }

      .hero {
        padding-top: 54px;
      }

      .hero h1 {
        font-size: 40px;
      }

      .guide-shell {
        border-radius: 24px;
      }

      .tabbar {
        top: 72px;
      }

      .os-head,
      .steps,
      .lesson-body,
      .lesson-top {
        padding: 18px;
      }

      .download-warning-layout,
      .drag-row,
      .about-body,
      .settings-body {
        grid-template-columns: 1fr;
      }

      .big-arrow {
        transform: rotate(90deg);
      }

      .settings-side {
        border-right: 0;
        border-bottom: 1px solid #E1E8F0;
      }

      .file-cards {
        grid-template-columns: 1fr;
      }

      .open-anyway-row {
        align-items: flex-start;
        flex-direction: column;
      }

      .smart-wrap {
        min-height: 420px;
        padding: 24px;
      }

      .smart-actions {
        left: 24px;
        right: 24px;
        justify-content: flex-end;
      }

      .mac-alert {
        margin: 18px auto;
        grid-template-columns: 1fr;
      }
    }
  
.brand-logo {
  background: url("../images/app-icon.webp") center / cover no-repeat !important;
  color: transparent !important;
  overflow: hidden;
}
.brand-logo img { display: block; width: 100%; height: 100%; object-fit: cover; }