:root {
  --bg: #ffffff;
  --bg-soft: #f7f7f8;
  --text: #1a1a1a;
  --text-soft: #5a5a66;
  --text-mute: #8a8a93;
  --border: #e6e6ea;
  --accent: #3b6df2;
  --accent-hover: #2c57d4;
  --radius: 12px;
  --max: 960px;
  --font-cn: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-en: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", system-ui, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --bg-soft: #15181f;
    --text: #ececf1;
    --text-soft: #b6b8c0;
    --text-mute: #7d8090;
    --border: #262934;
    --accent: #6e95ff;
    --accent-hover: #87a8ff;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-en), var(--font-cn);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  line-height: 1.65;
}

body[data-lang="zh"] { font-family: var(--font-cn), var(--font-en); }

a {
  color: var(--accent);
  text-decoration: none;
}
a:hover { color: var(--accent-hover); text-decoration: underline; }

.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(255,255,255,0.82);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
}
@media (prefers-color-scheme: dark) {
  .nav { background: rgba(15,17,21,0.78); }
}

.nav-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  gap: 16px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 16px;
  color: var(--text);
}
.brand img { width: 28px; height: 28px; border-radius: 6px; }

.nav-links {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 22px;
}
.nav-links a {
  color: var(--text-soft);
  font-size: 14px;
}
.nav-links a:hover { color: var(--text); text-decoration: none; }

.lang-toggle {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 999px;
  overflow: hidden;
  font-size: 12px;
  background: var(--bg);
}
.lang-toggle button {
  background: transparent;
  border: 0;
  color: var(--text-mute);
  padding: 6px 12px;
  cursor: pointer;
  font: inherit;
}
.lang-toggle button.active {
  background: var(--accent);
  color: #fff;
}

main { max-width: var(--max); margin: 0 auto; padding: 0 24px; }

.hero { padding: 88px 0 56px; text-align: center; }
.hero img.logo { width: 112px; height: 112px; border-radius: 24px; box-shadow: 0 10px 40px rgba(0,0,0,0.08); }
.hero h1 {
  font-size: 44px;
  margin: 24px 0 12px;
  letter-spacing: -0.02em;
  font-weight: 700;
}
.hero .tagline {
  font-size: 18px;
  color: var(--text-soft);
  margin: 0 auto 28px;
  max-width: 620px;
}

.cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  background: var(--accent);
  color: #fff;
  border-radius: 999px;
  font-weight: 500;
  font-size: 15px;
  transition: background .15s ease;
}
.cta:hover { background: var(--accent-hover); color: #fff; text-decoration: none; }

.cta-secondary {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 12px 18px;
  color: var(--text-soft);
  font-size: 14px;
}

.cta-row { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  padding: 32px 0 80px;
}
.feature {
  padding: 24px;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.feature h3 { margin: 0 0 8px; font-size: 16px; font-weight: 600; }
.feature p { margin: 0; color: var(--text-soft); font-size: 14px; }

article.doc {
  padding: 64px 0 96px;
}
article.doc h1 {
  font-size: 32px;
  margin: 0 0 8px;
  letter-spacing: -0.01em;
}
article.doc .updated {
  color: var(--text-mute);
  font-size: 13px;
  margin: 0 0 32px;
}
article.doc h2 {
  font-size: 20px;
  margin: 36px 0 12px;
  font-weight: 600;
}
article.doc p, article.doc li {
  color: var(--text-soft);
  font-size: 15px;
}
article.doc ul { padding-left: 1.4em; }
article.doc li { margin: 6px 0; }
article.doc a { word-break: break-all; }

footer {
  border-top: 1px solid var(--border);
  padding: 32px 24px;
  text-align: center;
  color: var(--text-mute);
  font-size: 13px;
}
footer .links { margin-bottom: 8px; }
footer .links a { color: var(--text-soft); margin: 0 10px; }

body[data-lang="zh"] .en,
body[data-lang="en"] .zh { display: none; }

@media (max-width: 640px) {
  .hero { padding: 56px 0 40px; }
  .hero h1 { font-size: 32px; }
  .hero .tagline { font-size: 16px; }
  .nav-links { gap: 14px; }
  .nav-links .nav-doc { display: none; }
}