:root {
  --bg: #FFFFFF;
  --bg-panel: #F4F6F8;
  --bg-panel-2: #EBEEF1;
  --border: #E2E6EA;
  --accent: #1FA2E5;
  --accent-dark: #0F7CB8;
  --text: #2E3338;
  --text-muted: #6B737B;
  --success: #2E9E6B;
  --warn: #D99A1E;
  --error: #D9483B;
  --on-accent: #FFFFFF;
  --clear: transparent;
  --accent-wash: color-mix(in srgb, var(--accent) 9%, var(--bg));
  --accent-line: color-mix(in srgb, var(--accent) 32%, var(--bg));
  --link-ink: color-mix(in srgb, var(--accent-dark) 85%, var(--text));
  --muted-panel-ink: color-mix(in srgb, var(--text-muted) 88%, var(--text));
  --row-tint: color-mix(in srgb, var(--bg-panel) 60%, var(--bg));
  --notch: color-mix(in srgb, var(--text-muted) 28%, var(--bg-panel-2));
  --wallpaper: linear-gradient(155deg, color-mix(in srgb, var(--accent) 17%, var(--bg)) 0%, color-mix(in srgb, var(--accent) 6%, var(--bg-panel)) 52%, var(--bg-panel-2) 100%);
  --lid-face: linear-gradient(180deg, var(--bg) 0%, var(--bg-panel) 100%);
  --deck-face: linear-gradient(180deg, var(--bg-panel-2) 0%, var(--border) 100%);
  --floor-face: linear-gradient(to bottom, var(--clear) 0, var(--bg-panel) 150px);
  --shadow-soft: 0 1px 2px rgba(46,51,56,.05), 0 12px 32px -8px rgba(46,51,56,.12);
  --shadow-deep: 0 2px 6px rgba(46,51,56,.08), 0 30px 60px -12px rgba(46,51,56,.26);
  --shadow-win: 0 1px 2px rgba(46,51,56,.06), 0 8px 20px -6px rgba(46,51,56,.14);
  --shadow-btn: 0 1px 2px rgba(46,51,56,.10), 0 6px 14px -6px rgba(46,51,56,.22);
  --ink-shadow: rgba(46,51,56,.16);
  --sheen: rgba(255,255,255,.22);
  --veil: rgba(46,51,56,.24);
  --font-display: "Inter", "Noto Sans SC", -apple-system, "PingFang SC", "Microsoft YaHei", "Hiragino Sans", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  --font-body: "Inter", "Noto Sans SC", -apple-system, "PingFang SC", "Microsoft YaHei", "Hiragino Sans", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --r-ctl: 6px;
  --r-card: 10px;
  --r-device: 14px;
  --r-phone: 26px;
  --r-screen: 20px;
  --r-window: 8px;
  --r-small: 5px;
  --r-mini: 4px;
  --r-mark: 2px;
  --r-hair: 1px;
  --r-toggle: 7px;
  --r-pill: 999px;
  --r-round: 50%;
  --gutter: 32px;
  --content-width: 1200px;
  --reading-width: 800px;
  --header-width: 1280px;
  --header-height: 64px;
  --size-body: 16px;
  --size-small: 14px;
  --size-note: 13px;
  --size-h1: clamp(34px, 3.2vw, 48px);
  --size-hero-approved: clamp(26px, 3.2vw, 46px);
  --size-h2: clamp(26px, 2.6vw, 36px);
  --size-h3: 22px;
  --weight-normal: 400;
  --weight-medium: 500;
  --weight-semibold: 600;
  --weight-bold: 700;
  --weight-brand: 800;
  --weight-display: 900;
  --tracking-display: -.02em;
  --tracking-approved: -.03em;
  --duration: .2s;
  --reveal-duration: .55s;
  --section-space: 96px;
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 24px; }
html.nav-open { overflow: hidden; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--size-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
img, svg { vertical-align: middle; }
img { max-width: 100%; height: auto; }
button, input, select, textarea { font: inherit; }
button, summary { cursor: pointer; }
button { color: var(--text); }
a { color: var(--link-ink); text-underline-offset: .2em; }
a:hover { text-decoration-thickness: 2px; }
:where(a, button, summary, input, select, textarea, [tabindex]):focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: var(--r-ctl);
}
[hidden] { display: none !important; }
h1, h2, h3 { font-family: var(--font-display); text-wrap: balance; overflow-wrap: normal; }
h1 { font-size: var(--size-h1); font-weight: var(--weight-display); line-height: 1.15; letter-spacing: var(--tracking-display); }
h2 { font-size: var(--size-h2); font-weight: var(--weight-display); line-height: 1.25; letter-spacing: var(--tracking-display); }
h3 { font-size: var(--size-h3); font-weight: var(--weight-bold); line-height: 1.4; }
p { margin-top: 0; }
code { font-family: var(--font-mono); overflow-wrap: anywhere; font-size: .9em; }
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 20px;
  background: var(--bg-panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-ctl);
  font-family: var(--font-mono);
  line-height: 1.7;
}
pre code { overflow-wrap: normal; white-space: pre; }
:where(.grid, .card-grid, .footer-grid, .reading-layout, .feature-switch, .split-row) > * { min-width: 0; }
:where(.icon, .dot, .eyebrow::before, .btn svg) { flex-shrink: 0; }
.wrap { max-width: var(--content-width); margin-inline: auto; padding-inline: var(--gutter); }
.reading-wrap { max-width: calc(var(--reading-width) + var(--gutter) * 2); margin-inline: auto; padding-inline: var(--gutter); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-panel { background: var(--bg-panel); color: var(--text); }
.section-heading { max-width: 760px; margin-bottom: 40px; }
.section-heading h2 { margin-top: 8px; margin-bottom: 16px; }
.section-heading p { color: var(--text-muted); }
.center { text-align: center; }
.center.section-heading { margin-inline: auto; }
.keep { white-space: nowrap; }
.muted { color: var(--text-muted); }
.small { font-size: var(--size-small); }
.mono { font-family: var(--font-mono); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
.skip-link { position: absolute; top: 8px; left: var(--gutter); z-index: 100; padding: 12px 16px; background: var(--bg); color: var(--text); }
.skip-link:not(:focus) { width: 1px; height: 1px; padding: 0; overflow: hidden; clip-path: inset(50%); white-space: nowrap; }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 9px 22px;
  border: 1px solid var(--clear);
  border-radius: var(--r-ctl);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: var(--weight-semibold);
  line-height: 24px;
  text-decoration: none;
  text-align: center;
  transition: background-color var(--duration), border-color var(--duration), color var(--duration);
}
.btn svg { width: 16px; height: 16px; }
.btn-primary { background: var(--accent); color: var(--on-accent); box-shadow: inset 0 1px 0 var(--sheen), var(--shadow-btn); }
.btn-primary:hover, .btn-primary.is-hover { background: var(--accent-dark); color: var(--on-accent); }
.btn-primary:active { background: var(--link-ink); color: var(--on-accent); }
.btn-ghost { background: var(--bg); color: var(--text); border-color: var(--border); }
.btn-ghost:hover, .btn-ghost.is-hover { border-color: var(--accent-line); color: var(--link-ink); }
.btn:disabled, .btn[aria-disabled="true"] { background: var(--bg-panel-2); color: var(--muted-panel-ink); border-color: var(--border); box-shadow: none; cursor: not-allowed; }
.btn.is-focus { outline: 2px solid var(--accent); outline-offset: 3px; }
.button-row { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.card, .panel {
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  background: var(--bg);
  color: var(--text);
}
.card { box-shadow: var(--shadow-soft); }
.card h3, .panel h3 { margin-top: 0; }
.card p:last-child, .panel p:last-child { margin-bottom: 0; }
.card-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.prose { min-width: 0; line-height: 1.85; }
.prose h2 { margin-top: 56px; margin-bottom: 20px; scroll-margin-top: 24px; }
.prose h3 { margin-top: 32px; }
.prose li + li { margin-top: 8px; }
.prose :where(p, li, dd, a) { overflow-wrap: break-word; }
.prose code { overflow-wrap: anywhere; }
.prose pre code { overflow-wrap: normal; }
.prose img { height: auto; }
.prose > :first-child { margin-top: 0; }
.decorated-section, .hero { position: relative; overflow-x: clip; }
.reveal { opacity: 1; }
.reveal-ready .reveal:not(.shown) { opacity: 0; transform: translateY(16px); }
.reveal-ready .reveal { transition: opacity var(--reveal-duration), transform var(--reveal-duration); }
.reveal.shown { opacity: 1; transform: none; }

/* 页头：独立宽版心，品牌、导航、工具、抽屉互为兄弟节点。 */
.topbar { height: var(--header-height); position: relative; z-index: 50; border-bottom: 1px solid var(--border); background: var(--bg); color: var(--text); }
.header-inner {
  max-width: min(100%, calc(var(--header-width) + var(--gutter) * 2));
  height: 100%;
  padding-inline: var(--gutter);
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: 24px;
}
.brand { display: flex; align-items: center; gap: 10px; flex-shrink: 0; text-decoration: none; color: var(--text); font-family: var(--font-display); font-size: 16.5px; font-weight: var(--weight-brand); letter-spacing: -.01em; }
.brand img { width: 30px; height: 30px; flex-shrink: 0; }
.mainnav { margin-left: auto; min-width: 0; }
.mainnav ul { display: flex; align-items: center; list-style: none; margin: 0; padding: 0; gap: 30px; }
.mainnav a { display: block; padding-block: 10px; white-space: nowrap; font-size: 14.5px; font-weight: var(--weight-medium); color: var(--text-muted); text-decoration: none; }
.mainnav a:hover { color: var(--text); }
.mainnav a[aria-current="page"] { color: var(--text); font-weight: var(--weight-bold); }
.header-tools { position: relative; display: flex; align-items: center; flex-shrink: 0; gap: 8px; }
.lang-button { display: inline-flex; align-items: center; gap: 6px; min-height: 44px; padding: 0 0 0 28px; border: 0; border-left: 1px solid var(--border); background: var(--bg); color: var(--text); font-size: var(--size-small); font-weight: var(--weight-medium); white-space: nowrap; }
.lang-caret { color: var(--text-muted); font-size: 12px; }
.lang-short { display: none; }
.language-menu { position: absolute; right: 0; top: calc(100% + 8px); width: 190px; margin: 0; padding: 6px; list-style: none; border: 1px solid var(--border); border-radius: var(--r-card); background: var(--bg); color: var(--text); box-shadow: var(--shadow-soft); z-index: 4; }
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 10px 12px; color: var(--text); text-decoration: none; border-radius: var(--r-ctl); }
.language-menu a:hover, .language-menu a[aria-current="true"] { background: var(--bg-panel); color: var(--text); }
.menu-button { display: none; align-items: center; justify-content: center; min-width: 44px; min-height: 44px; border: 1px solid var(--border); border-radius: var(--r-ctl); background: var(--bg); color: var(--text); }
.menu-button svg { width: 20px; height: 20px; }
.mobile-drawer { display: none; position: absolute; top: 100%; left: 0; right: 0; max-height: calc(100dvh - var(--header-height)); overflow-y: auto; overscroll-behavior: contain; padding: 16px var(--gutter) 24px; border-bottom: 1px solid var(--border); background: var(--bg); color: var(--text); z-index: 3; }
.mobile-drawer ul { margin: 0; padding: 0; list-style: none; }
.mobile-drawer a { display: flex; align-items: center; width: 100%; min-height: 44px; padding: 10px 12px; color: var(--text); text-decoration: none; border-radius: var(--r-ctl); }
.mobile-drawer a:hover, .mobile-drawer a[aria-current] { background: var(--bg-panel); color: var(--text); }
.mobile-languages { margin-top: 16px !important; padding-top: 16px !important; border-top: 1px solid var(--border); }
.nav-veil { position: fixed; inset: var(--header-height) 0 0; border: 0; padding: 0; background: var(--veil); color: var(--text); z-index: 40; }

/* 页脚 */
.site-footer { padding-top: 64px; padding-bottom: 28px; border-top: 1px solid var(--border); background: var(--bg-panel); color: var(--text); }
.footer-grid { display: grid; grid-template-columns: 1.2fr .8fr 1.6fr; gap: 48px; }
.footer-brand p { max-width: 320px; margin-top: 18px; font-size: var(--size-small); color: var(--muted-panel-ink); }
.footer-title { margin: 0 0 16px; font-size: var(--size-small); font-weight: var(--weight-bold); }
.footer-links { padding: 0; margin: 0; list-style: none; display: grid; gap: 8px; }
.footer-links a, .footer-languages a, .footer-bottom a { color: var(--muted-panel-ink); font-size: var(--size-small); text-decoration: none; }
.footer-links a:hover, .footer-languages a:hover, .footer-bottom a:hover { color: var(--link-ink); text-decoration: underline; }
.footer-searches { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.footer-languages { display: flex; flex-wrap: wrap; gap: 12px 24px; padding-top: 32px; padding-bottom: 24px; }
.footer-languages a[aria-current] { color: var(--text); font-weight: var(--weight-bold); }
.footer-bottom { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 16px; padding-top: 24px; border-top: 1px solid var(--border); font-size: var(--size-note); color: var(--muted-panel-ink); }

/* 已确认的首页首屏排版。 */
.hero { padding-top: 28px; padding-bottom: 56px; text-align: center; }
.hero-floor { position: absolute; inset: auto 0 0; height: 256px; background: var(--floor-face); color: var(--text); z-index: 0; pointer-events: none; }
.hero-copy, .rig { position: relative; z-index: 1; }
.eyebrow { display: inline-flex; align-items: center; gap: 8px; min-height: 26px; padding: 4px 12px 4px 10px; margin: 0; border: 1px solid var(--border); border-radius: var(--r-pill); background: var(--bg); color: var(--text-muted); font-size: 12.5px; font-weight: var(--weight-medium); line-height: 1; max-width: 100%; }
.eyebrow::before { content: ""; width: 6px; height: 6px; border-radius: var(--r-round); background: var(--accent); }
.title { margin: 16px 0 0; font-family: var(--font-display); font-weight: var(--weight-display); font-size: var(--size-hero-approved); line-height: 1.12; letter-spacing: var(--tracking-approved); color: var(--text); }
.title-line { display: block; }
.lede { margin: 12px auto 0; max-width: 720px; font-size: 17px; line-height: 1.6; color: var(--text-muted); }
.lede strong { color: var(--text); font-weight: var(--weight-semibold); }
.cta { margin-top: 22px; display: flex; justify-content: center; gap: 12px; }
.os-row { margin: 20px 0 0; padding: 0; list-style: none; display: flex; justify-content: center; align-items: center; }
.os-row li { padding-inline: 20px; font-size: 13.5px; font-weight: var(--weight-medium); line-height: 20px; color: var(--text-muted); }
.os-row li + li { border-left: 1px solid var(--border); }
.os-row a { display: flex; align-items: center; gap: 7px; color: inherit; text-decoration: none; }
.os-row svg { width: 15px; height: 15px; flex-shrink: 0; }
.proto-row { margin: 12px 0 0; padding: 0; list-style: none; display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; }
.proto-row li { display: inline-flex; align-items: center; min-height: 24px; padding: 2px 10px; border: 1px solid var(--border); border-radius: var(--r-pill); background: var(--bg-panel); color: var(--muted-panel-ink); font-family: var(--font-mono); font-size: 11.5px; letter-spacing: .01em; max-width: 100%; overflow-wrap: anywhere; }
.next { background: var(--bg-panel); color: var(--text); padding-top: 8px; padding-bottom: 96px; text-align: center; }
.next-kicker { margin: 0; font-size: 13px; font-weight: var(--weight-semibold); color: var(--link-ink); letter-spacing: .02em; }
.next-title { margin: 10px 0 0; font-family: var(--font-display); font-weight: var(--weight-display); font-size: 28px; line-height: 1.25; letter-spacing: var(--tracking-display); color: var(--text); }

@media (max-width: 1180px) {
  .mainnav ul { gap: 20px; }
  .header-inner { gap: 20px; }
  .lang-button { padding-left: 18px; }
}
@media (max-width: 1080px) {
  .mainnav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-button { display: inline-flex; }
  .lang-button { border-left: 0; padding-left: 0; }
  .mobile-drawer:not([hidden]) { display: block; }
}
@media (max-width: 860px) {
  .card-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .footer-brand { grid-column: 1 / -1; }
}
@media (max-width: 768px) {
  h1 { font-size: clamp(24px, 4vw, 30px); }
  .title { font-size: clamp(24px, 4vw, 30px); letter-spacing: var(--tracking-display); }
}
@media (max-width: 640px) {
  :root { --gutter: 20px; --section-space: 64px; }
  .header-inner { gap: 8px; }
  .header-tools { margin-left: auto; }
  .brand { font-size: 14px; gap: 7px; }
  .brand img { width: 28px; height: 28px; }
  .lang-full { display: none; }
  .lang-short { display: inline; }
  .card-grid, .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-brand { grid-column: auto; }
  .footer-searches { grid-template-columns: minmax(0, 1fr); }
  .card, .panel { padding: 22px; }
  .lede { font-size: 15.5px; }
  .cta { flex-direction: column; align-items: stretch; max-width: 320px; margin-inline: auto; }
  .os-row { flex-wrap: wrap; row-gap: 8px; }
  .os-row li { padding-inline: 12px; }
  .proto-row { padding-inline: 12px; }
  .hero-floor { height: 200px; }
  .tilt, [data-tilt] { transform: none !important; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
  .reveal-ready .reveal:not(.shown) { opacity: 1; transform: none; }
}