:root {
  --bg: #f6f7fb; --surface: #ffffff; --ink: #11151f; --muted: #5d6476; --line: #e2e5ee;
  --accent: #2f6fe4; --accent-ink: #ffffff; --hero: #0b1020; --hero-ink: #eef1fa; --hero-muted: #a8b1cc;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Helvetica Neue", Arial, sans-serif;
  --mono: "SF Mono", ui-monospace, Menlo, Consolas, monospace;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #0c0f17; --surface: #141925; --ink: #e9ecf3; --muted: #9aa2b4; --line: #252b3a; --accent: #6d9cff; --accent-ink: #0c0f17; }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font-family: var(--font); font-size: 16px; line-height: 1.65; }
a { color: var(--accent); }
img { max-width: 100%; display: block; }

/* One language at a time: English unless the browser prefers Chinese or ?lang=zh. */
:root:not([data-l="zh"]) [lang="zh"] { display: none !important; }
:root[data-l="zh"] [lang="en"] { display: none !important; }

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.narrow { max-width: 760px; }

.top { position: sticky; top: 0; z-index: 10; background: color-mix(in srgb, var(--bg) 86%, transparent); backdrop-filter: blur(12px); border-bottom: 1px solid var(--line); }
.top .wrap { display: flex; align-items: center; gap: 14px; height: 56px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font-weight: 650; }
.brand img { width: 28px; height: 28px; border-radius: 7px; }
.top nav { margin-left: auto; display: flex; gap: 18px; font-size: 14px; }
.top nav a { color: var(--muted); text-decoration: none; }
.top nav a:hover, .top nav a[aria-current] { color: var(--ink); }
.langswitch { font-size: 13px; border: 1px solid var(--line); border-radius: 999px; padding: 3px 10px; color: var(--muted); text-decoration: none; }

.hero { background: radial-gradient(ellipse at 70% 0%, rgba(80, 120, 255, .35), transparent 60%), var(--hero); color: var(--hero-ink); }
.hero .wrap { display: grid; grid-template-columns: 1.05fr .95fr; gap: 40px; align-items: center; padding-top: 72px; padding-bottom: 72px; }
.hero .icon { width: 72px; height: 72px; border-radius: 17px; box-shadow: 0 10px 30px rgba(0,0,0,.4); }
.hero h1 { font-size: clamp(34px, 5vw, 56px); line-height: 1.08; letter-spacing: -.02em; margin: 22px 0 14px; text-wrap: balance; }
.hero p.lead { color: var(--hero-muted); font-size: 19px; margin: 0 0 28px; max-width: 34em; }
.hero .shots { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.hero .shots img { border-radius: 16px; box-shadow: 0 20px 50px rgba(0,0,0,.45); }
.hero .shots img:first-child { transform: translateY(26px); }
.cta { display: flex; flex-wrap: wrap; gap: 12px; }
.btn { display: inline-flex; align-items: center; gap: 8px; padding: 12px 20px; border-radius: 12px; font-weight: 600; text-decoration: none; font-size: 15px; }
.btn.primary { background: #ffffff; color: #0b1020; }
.btn.ghost { border: 1px solid rgba(255,255,255,.25); color: var(--hero-ink); }
.note { color: var(--hero-muted); font-size: 13px; margin-top: 14px; }

.section { padding: 72px 0; }
.section h2 { font-size: clamp(26px, 3.4vw, 34px); line-height: 1.2; margin: 0 0 10px; letter-spacing: -.01em; text-wrap: balance; }
.section p.sub { color: var(--muted); margin: 0 0 32px; max-width: 40em; }
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: 18px; padding: 22px; }
.card h3 { margin: 0 0 6px; font-size: 17px; }
.card p { margin: 0; color: var(--muted); font-size: 15px; }
.feature { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; align-items: center; }
.feature img { border-radius: 18px; border: 1px solid var(--line); }
.feature + .feature { margin-top: 56px; }

.doc { padding: 56px 0 80px; }
.doc h1 { font-size: clamp(28px, 4vw, 38px); margin: 0 0 6px; }
.doc .meta { font-family: var(--mono); color: var(--muted); font-size: 13px; margin-bottom: 26px; }
.doc h2 { font-size: 20px; margin: 34px 0 8px; }
.doc li { margin: 4px 0; }
.doc .box { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 18px 20px; }
details { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 14px 18px; margin: 10px 0; }
summary { cursor: pointer; font-weight: 600; }
details p { color: var(--muted); margin: 10px 0 0; }
code { font-family: var(--mono); font-size: .92em; background: var(--line); padding: 1px 5px; border-radius: 5px; }

footer { border-top: 1px solid var(--line); padding: 28px 0 40px; color: var(--muted); font-size: 14px; }
footer .wrap { display: flex; flex-wrap: wrap; gap: 18px; align-items: center; }
footer nav { margin-left: auto; display: flex; gap: 18px; }
footer a { color: var(--muted); }

@media (max-width: 820px) {
  .hero .wrap, .feature { grid-template-columns: 1fr; }
  .grid { grid-template-columns: 1fr; }
  .top nav { gap: 12px; }
  .top nav a.hide-sm { display: none; }
  .hero .shots img:first-child { transform: none; }
}