/*
 * VBox 官网样式
 *
 * 单文件、免构建：重置 + 组件一次加载。
 * 组件与站点其余页面共用一套命名（topbar / hero / section / card / footer / btt），
 * 加页面只需引这一个文件。
 */

/* ── 重置 ───────────────────────────────────────────── */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
html {
  scroll-behavior: smooth;
  scroll-padding-top: 72px;
}
body {
  font:
    16px/1.8 system-ui,
    -apple-system,
    'Segoe UI',
    'Noto Sans SC',
    sans-serif;
  color: #303030;
  background: #fafafa;
  -webkit-text-size-adjust: 100%;
}
a {
  color: #03a9f4;
}
img {
  max-width: 100%;
}
code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
  background: #eef6fc;
  border-radius: 4px;
  padding: 1px 5px;
}
:focus-visible {
  outline: 2px solid #03a9f4;
  outline-offset: 2px;
}

/* ── 顶栏 ───────────────────────────────────────────── */
.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 20px;
  background: rgba(250, 250, 250, 0.8);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}
.topbar .brand {
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
}
.topbar .brand img {
  width: 28px;
  height: 28px;
  display: block;
}
.topbar .brand-text {
  font-size: 16px;
  font-weight: 700;
  color: #03a9f4;
}
.topbar .links {
  display: flex;
  align-items: center;
  gap: 4px;
}
.topbar .links a {
  padding: 5px 14px;
  border-radius: 16px;
  background: rgba(3, 169, 244, 0.1);
  border: 1px solid rgba(3, 169, 244, 0.25);
  color: #03a9f4;
  text-decoration: none;
  font-size: 13px;
  transition:
    background 0.2s,
    color 0.2s,
    border-color 0.2s;
}
.topbar .links a:hover {
  background: #03a9f4;
  border-color: #03a9f4;
  color: #fff;
}
.topbar .links a[aria-current='page'] {
  background: #03a9f4;
  border-color: #03a9f4;
  color: #fff;
  box-shadow: 0 0 0 2px rgba(3, 169, 244, 0.3);
}

/* ── 首屏 ───────────────────────────────────────────── */
.hero {
  text-align: center;
  background: linear-gradient(135deg, #e3f2fd, #fafafa);
  padding: 100px 20px 60px;
}
.hero h1 {
  font-size: 36px;
  color: #03a9f4;
  margin-bottom: 12px;
}
.hero p {
  color: #757575;
  font-size: 18px;
  margin: 0 auto;
  max-width: 480px;
}
.cta {
  margin-top: 24px;
  display: flex;
  justify-content: center;
  align-items: stretch;
  gap: 12px;
  flex-wrap: wrap;
}
.cta a {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  padding: 16px 32px;
  border-radius: 24px;
  text-decoration: none;
  font-size: 16px;
  min-height: 64px;
  line-height: 1.4;
}
.cta .primary {
  background: #03a9f4;
  color: #fff;
}
.cta .primary small {
  font-size: 12px;
  opacity: 0.8;
  font-weight: 400;
}
.cta .secondary {
  background: #e3f2fd;
  border: 1px solid #03a9f4;
  color: #03a9f4;
}
.cta .secondary:hover {
  background: #bbdefb;
}

/* ── 版块 ───────────────────────────────────────────── */
.section {
  max-width: 800px;
  margin: 0 auto;
  padding: 48px 20px;
}
.section h2 {
  color: #03a9f4;
  font-size: 22px;
  margin-bottom: 16px;
}
.section .lead {
  color: #757575;
  font-size: 15px;
  margin-bottom: 8px;
}

/* ── 卡片 ───────────────────────────────────────────── */
.card {
  background: #fff;
  border-radius: 12px;
  padding: 24px;
  margin: 16px 0;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.06);
}
.card h3 {
  color: #303030;
  margin-bottom: 8px;
  font-size: 17px;
}
.card p {
  color: #757575;
  font-size: 14px;
}
.card p + p {
  margin-top: 8px;
}
a.card-link {
  display: block;
  text-decoration: none;
  color: inherit;
}
a.card-link .card {
  transition: box-shadow 0.2s;
}
a.card-link .card:hover {
  box-shadow: 0 3px 12px rgba(0, 0, 0, 0.1);
}
.card .more {
  color: #03a9f4;
  margin-top: 8px;
}

/* ── 文档式长页（隐私政策 / 用户协议） ──────────────── */
.doc {
  max-width: 760px;
  margin: 0 auto;
  padding: 100px 20px 48px;
}
.doc h1 {
  font-size: 26px;
  color: #03a9f4;
  margin-bottom: 8px;
}
.doc .updated {
  color: #999;
  font-size: 13px;
  margin-bottom: 24px;
}
.doc h2 {
  font-size: 18px;
  color: #303030;
  margin: 28px 0 10px;
}
.doc p,
.doc li {
  color: #555;
  font-size: 15px;
}
.doc ul {
  padding-left: 22px;
}
.doc li {
  margin: 4px 0;
}

/* ── 页脚 ───────────────────────────────────────────── */
.footer {
  text-align: center;
  padding: 32px 20px;
  color: #999;
  font-size: 13px;
  border-top: 1px solid #e0e0e0;
  margin-top: 24px;
}
.footer a {
  color: #999;
  text-decoration: none;
}
.footer img {
  width: 16px;
  height: 16px;
  vertical-align: middle;
  margin-right: 2px;
}

/* ── 回到顶部 ───────────────────────────────────────── */
.btt {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid rgba(0, 0, 0, 0.12);
  background: #fff;
  color: #999;
  font-size: 18px;
  cursor: pointer;
  z-index: 90;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s;
}
.btt.on {
  opacity: 0.85;
  pointer-events: auto;
}

/* ── 响应式 ─────────────────────────────────────────── */
@media (min-width: 768px) and (max-width: 1024px) {
  .hero {
    padding: 64px 24px 48px;
  }
  .hero h1 {
    font-size: 30px;
  }
  .hero p {
    font-size: 16px;
  }
  .section {
    max-width: 720px;
    padding: 40px 24px;
  }
}
@media (max-width: 767px) {
  .hero {
    padding: 60px 16px 32px;
  }
  .hero h1 {
    font-size: 24px;
  }
  .hero p {
    font-size: 15px;
  }
  .cta {
    flex-direction: column;
    align-items: center;
  }
  .cta a {
    width: 100%;
    max-width: 240px;
  }
  .section {
    padding: 28px 16px;
  }
  .section h2 {
    font-size: 18px;
  }
  .card {
    padding: 16px;
  }
  .topbar {
    padding: 8px 12px;
  }
  .topbar .brand {
    flex-shrink: 0;
  }
  .topbar .brand img {
    width: 24px;
    height: 24px;
  }
  .topbar .brand-text {
    font-size: 12px;
  }
  .topbar .links {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }
  .topbar .links::-webkit-scrollbar {
    display: none;
  }
  .topbar .links a {
    flex-shrink: 0;
    padding: 4px 10px;
    font-size: 12px;
  }
  .doc {
    padding: 84px 16px 40px;
  }
}