:root {
    --bg-top: #f6f8ff;
    --bg-bottom: #e9f0ff;
    --title: #1f2937;
    --body: #6b7280;
    --link: #4f46e5;
    --link-hover: #1d4ed8;
    --toggle-bg: rgba(255, 255, 255, 0.8);
    --toggle-border: rgba(31, 41, 55, 0.12);
    --toggle-text: #1f2937;
    --menu-bg: rgba(255, 255, 255, 0.92);
    --menu-border: rgba(31, 41, 55, 0.12);
    --menu-text: #1f2937;
    --menu-shadow: 0 18px 40px rgba(15, 23, 42, 0.12);
  }

  html[data-theme="dark"] {
    --bg-top: #0d1424;
    --bg-bottom: #06080f;
    --title: #e5e7eb;
    --body: #9ca3af;
    --link: #9bb2ff;
    --link-hover: #c7d2fe;
    --toggle-bg: rgba(16, 19, 30, 0.8);
    --toggle-border: rgba(148, 163, 184, 0.25);
    --toggle-text: #e5e7eb;
    --menu-bg: rgba(16, 19, 30, 0.92);
    --menu-border: rgba(148, 163, 184, 0.2);
    --menu-text: #e5e7eb;
    --menu-shadow: 0 18px 40px rgba(3, 7, 18, 0.45);
  }

  * {
    box-sizing: border-box;
  }

  body {
    margin: 0;
    height: 100vh;
    overflow: hidden;
    font-family: "SF Pro Display", "SF Pro Text", "Helvetica Neue", "Noto Sans SC", sans-serif;
    background: linear-gradient(180deg, var(--bg-top), var(--bg-bottom));
    color: var(--title);
  }

  html[data-lang="zh"] body {
    font-size: 0.94em;
  }

  .hero {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
  }

  .hero-inner {
    max-width: 720px;
    text-align: left;
  }

  .app-list {
    display: flex;
    flex-direction: column;
    gap: 28px;
  }

  .hero-title {
    font-size: clamp(1.15rem, 2.2vw, 1.6rem);
    font-weight: 600;
    margin: 0 0 20px;
    letter-spacing: -0.01em;
  }

  .app {
    margin: 0 0 28px;
  }

  .app-name {
    font-size: clamp(1rem, 1.8vw, 1.2rem);
    font-weight: 600;
    margin: 0 0 10px;
  }

  .app-desc {
    margin: 0;
    font-size: clamp(0.92rem, 1.6vw, 1.05rem);
    color: var(--body);
    line-height: 1.7;
  }

  .app-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: inherit;
    text-decoration: none;
    transition: transform 0.25s ease;
    will-change: transform;
  }

  .app-arrow {
    font-size: 0.95em;
  }

  .shimmer-hover {
    --text-color: currentColor;
    color: var(--text-color);
    background-image: linear-gradient(90deg, var(--text-color), var(--text-color));
    background-size: 100% 100%;
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
  }

  .shimmer-hover:hover {
    background-image: linear-gradient(
      90deg,
      var(--link-hover) 20%,
      #93c5fd 45%,
      var(--link-hover) 70%
    );
    background-size: 200% auto;
    animation: shimmer 2.6s linear infinite;
  }

  .top-controls {
    position: fixed;
    top: 20px;
    right: 24px;
    display: flex;
    gap: 10px;
    z-index: 2;
  }

  .control-btn {
    border: 1px solid var(--toggle-border);
    background: var(--toggle-bg);
    color: var(--toggle-text);
    font-size: 0.9rem;
    padding: 8px 12px;
    border-radius: 999px;
    cursor: pointer;
    transition: border-color 0.2s ease, transform 0.2s ease;
  }

  .control-btn.icon-btn {
    width: 38px;
    height: 38px;
    padding: 0;
    display: grid;
    place-items: center;
  }

  .control-btn svg {
    width: 18px;
    height: 18px;
    stroke: currentColor;
  }

  .icon-sun {
    display: none;
  }

  html[data-theme="dark"] .icon-sun {
    display: block;
  }

  html[data-theme="dark"] .icon-moon {
    display: none;
  }

  .control-btn:hover {
    transform: translateY(-1px);
    border-color: var(--link-hover);
  }

  .control-btn:hover,
  .app-link:hover,
  .menu-panel a:hover,
  .footer-links .shimmer-hover:hover {
    transform: scale(1.04);
  }

  .product-menu {
    position: relative;
    width: 170px;
    display: flex;
    justify-content: flex-end;
  }

  .product-menu::after {
    content: "";
    position: absolute;
    top: 38px;
    left: 0;
    right: 0;
    height: 14px;
  }

  .menu-panel {
    position: absolute;
    top: 52px;
    right: 0;
    min-width: 160px;
    background: var(--menu-bg);
    border: 1px solid var(--menu-border);
    border-radius: 14px;
    box-shadow: var(--menu-shadow);
    padding: 8px;
    opacity: 0;
    transform: translateY(-10px) scaleY(0.96);
    transform-origin: top right;
    pointer-events: none;
    filter: blur(6px);
    transition: opacity 0.28s ease, transform 0.28s ease, filter 0.28s ease;
    will-change: transform, opacity;
  }

  .menu-panel a {
    display: block;
    padding: 10px 12px 10px 32px;
    border-radius: 10px;
    color: var(--menu-text);
    text-decoration: none;
    font-size: 0.95rem;
    position: relative;
    overflow: hidden;
    transition: transform 0.25s ease, color 0.25s ease, background 0.25s ease;
  }

  .menu-panel a::before {
    content: "→";
    position: absolute;
    left: 10px;
    top: 50%;
    font-size: 0.9rem;
    color: var(--link-hover);
    transform: translate(-10px, -50%);
    opacity: 0;
    transition: transform 0.25s ease, opacity 0.25s ease;
  }

  .menu-panel a:hover {
    background: transparent;
    color: var(--link-hover);
    transform: translateX(4px) scale(1.04);
  }

  .menu-panel a:hover::before {
    opacity: 1;
    transform: translate(0, -50%);
  }

  .product-menu:hover .menu-panel,
  .product-menu.open .menu-panel {
    opacity: 1;
    transform: translateY(0) scaleY(1);
    filter: blur(0);
    pointer-events: auto;
  }

  @keyframes shimmer {
    0% {
      background-position: 200% 50%;
    }
    100% {
      background-position: -200% 50%;
    }
  }

  .footer-links {
    position: fixed;
    left: 24px;
    right: 24px;
    bottom: 18px;
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
    font-size: 0.95rem;
    color: var(--body);
  }

  .footer-links a {
    color: inherit;
    text-decoration: none;
    transition: color 0.2s ease;
  }

  @media (max-width: 640px) {
    body {
      height: auto;
      min-height: 100vh;
      overflow: hidden;
      font-size: 17px;
    }

    .hero {
      align-items: flex-start;
      height: 100vh;
      padding: 120px 24px 120px;
    }

    .hero-inner {
      max-width: 100%;
      width: 100%;
      max-height: calc(100vh - 200px);
      overflow: auto;
    }

    .hero-title {
      font-size: clamp(1.8rem, 6vw, 2.2rem);
    }

    .app-name {
      font-size: clamp(1.25rem, 4.8vw, 1.5rem);
    }

    .app-desc {
      font-size: clamp(1.05rem, 3.8vw, 1.2rem);
    }

    .top-controls {
      top: 16px;
      right: 16px;
    }

    .footer-links {
      position: fixed;
      bottom: 14px;
      left: 16px;
      right: 16px;
      font-size: 1.05rem;
      gap: 10px 16px;
    }
  }

  .footer-links .shimmer-hover {
    display: inline-block;
    transition: transform 0.25s ease;
  }

  .footer-links .shimmer-hover:hover {
    transform: scale(1.04);
  }