:root {
  --bg: #FFFFFF;
  --bg-panel: #F5F6F8;
  --bg-panel-2: #EDEEF1;
  --border: #E3E5E9;
  --border-strong: #D3D6DC;
  --dot: #CDD0D6;
  --accent: #2156D9;
  --accent-dark: #173FA8;
  --accent-soft: #E9EFFC;
  --accent-2: #9A5BE6;
  --text: #16181D;
  --text-muted: #5C6270;
  --text-faint: #8A909C;
  --success: #1F8A4C;
  --warn: #B7791F;
  --error: #C9372C;
  --veil: rgba(22, 24, 29, .24);
  --clear: transparent;

  --font-display: 'Inter','Noto Sans SC','PingFang SC','Microsoft YaHei',system-ui,sans-serif;
  --font-body: 'Inter','Noto Sans SC','PingFang SC','Microsoft YaHei',system-ui,-apple-system,'Segoe UI',sans-serif;
  --font-mono: 'JetBrains Mono',ui-monospace,'Cascadia Code',Consolas,'SFMono-Regular',Menlo,monospace;
  --weight-body: 400;
  --weight-medium: 500;
  --weight-semibold: 650;
  --weight-bold: 750;
  --weight-display: 900;
  --text-xs: 12px;
  --text-sm: 14px;
  --text-base: 16px;
  --text-lead: 18px;
  --h1: clamp(34px, 3.4vw, 48px);
  --h2: clamp(28px, 3vw, 40px);
  --h3: clamp(22px, 2.4vw, 32px);
  --tracking-title: -.02em;
  --leading-body: 1.6;
  --leading-title: 1.15;

  --r-pill: 999px;
  --r-board: 24px;
  --r-panel: 20px;
  --r-float: 16px;
  --r-card: 12px;
  --r-chip: 8px;
  --r-round: 50%;

  --shadow-card: 0 1px 2px rgba(22,24,29,.06),0 12px 32px rgba(22,24,29,.07);
  --shadow-float: 0 1px 2px rgba(22,24,29,.06),0 16px 36px rgba(22,24,29,.10);
  --shadow-lift: 0 1px 2px rgba(22,24,29,.07),0 24px 48px rgba(22,24,29,.16);
  --shadow-soft: 0 1px 2px rgba(22,24,29,.04),0 10px 24px rgba(22,24,29,.06);
  --shadow-knob: 0 1px 2px rgba(22,24,29,.28);
  --shadow-cta: 0 6px 18px rgba(33,86,217,.22);
  --ring: 0 0 0 3px rgba(33,86,217,.30);
  --gutter: 24px;
  --reading-width: 820px;
  --content-width: 1180px;
  --header-width: 1280px;
  --nav-h: 72px;
  --peek: 24px;
  --stage-h: 440px;
  --section-space: 104px;
  --fast: .15s;
  --fade: .24s;
  --reveal-time: .6s;
  --ease: ease;
}

*, *::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: var(--weight-body) var(--text-base)/var(--leading-body) var(--font-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img, svg, video { max-width: 100%; }
img { height: auto; }
button, input, select, textarea { font: inherit; }
button, a { -webkit-tap-highlight-color: var(--clear); }
button { cursor: pointer; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-dark); }
:where(a, button, input, select, textarea, summary, [tabindex]):focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  box-shadow: var(--ring);
}
[hidden] { display: none !important; }
p { margin: 0; }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--text);
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1, h2, h3 { letter-spacing: var(--tracking-title); line-height: var(--leading-title); }
h1 { font-size: var(--h1); font-weight: var(--weight-display); }
h2 { font-size: var(--h2); font-weight: var(--weight-display); }
h3 { font-size: var(--h3); font-weight: 800; }
h4 { font-size: var(--text-lead); }
:where(section, article, aside, nav, main, div) { min-width: 0; }
:where([id]) { scroll-margin-top: 24px; }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; }
pre {
  max-width: 100%;
  margin: 24px 0;
  padding: 20px;
  overflow-x: auto;
  background: var(--bg-panel);
  color: var(--text);
  border-radius: var(--r-card);
  font-size: var(--text-sm);
  overscroll-behavior-inline: contain;
}
pre code { white-space: pre; overflow-wrap: normal; word-break: normal; }
blockquote { margin-inline: 0; }
.wrap {
  width: 100%;
  max-width: calc(var(--content-width) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.reading { max-width: calc(var(--reading-width) + var(--gutter) * 2); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-heading { margin: 0 0 24px; }
.lead { font-size: var(--text-lead); color: var(--text-muted); }
.muted { color: var(--text-muted); }
.mono { font-family: var(--font-mono); }
.keep { white-space: nowrap; }
.center { text-align: center; }
.stack > * + * { margin-top: 20px; }
.grid { display: grid; gap: 24px; }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid > *, .row > * { min-width: 0; }
.row { display: flex; align-items: center; flex-wrap: wrap; gap: 12px; }
.icon { width: 20px; height: 20px; flex-shrink: 0; }
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}
.skip-link {
  position: absolute;
  left: var(--gutter);
  top: -100px;
  z-index: 100;
  padding: 12px 20px;
  background: var(--bg);
  color: var(--accent);
  border-radius: var(--r-pill);
}
.skip-link:focus { top: 12px; }

.btn, .btn-primary, .btn-secondary, .text-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 50px;
  padding: 10px 24px;
  border: 1px solid var(--clear);
  border-radius: var(--r-pill);
  font-family: var(--font-display);
  font-size: var(--text-base);
  font-weight: 700;
  line-height: 1.4;
  text-align: center;
  transition: background-color var(--fast) var(--ease), color var(--fast) var(--ease), border-color var(--fast) var(--ease);
}
.btn-primary { background: var(--accent); color: var(--bg); box-shadow: var(--shadow-cta); }
.btn-primary:hover, .btn-primary.is-hover { background: var(--accent-dark); color: var(--bg); }
.btn-secondary { background: var(--bg); color: var(--text); border-color: var(--border-strong); }
.btn-secondary:hover { background: var(--bg-panel); color: var(--text); border-color: var(--text-muted); }
.text-link { padding-inline: 4px; color: var(--accent); }
.text-link span { display: inline-block; transition: transform var(--fast) var(--ease); }
.text-link:hover span { transform: translateX(3px); }
.btn-primary svg, .btn-secondary svg { width: 18px; height: 18px; flex-shrink: 0; }
:where(.btn, .btn-primary, .btn-secondary):disabled,
:where(.btn, .btn-primary, .btn-secondary)[aria-disabled="true"] {
  background: var(--bg-panel-2);
  color: var(--text-muted);
  border-color: var(--border);
  box-shadow: none;
  cursor: not-allowed;
}
.is-focus { box-shadow: var(--ring); }

.topbar, #site-header {
  position: relative;
  z-index: 40;
  background: var(--bg);
  color: var(--text);
}
.topbar__inner {
  max-width: min(100%, calc(var(--header-width) + var(--gutter) * 2));
  height: var(--nav-h);
  padding-inline: var(--gutter);
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: 44px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; flex-shrink: 0; color: var(--text); }
.brand:hover { color: var(--text); }
.brand__mark { display: block; width: 32px; height: 32px; flex-shrink: 0; }
.brand__name { font: 800 17px/1.3 var(--font-display); letter-spacing: -.01em; }
.mainnav { flex: 1; min-width: 0; }
.mainnav ul {
  display: flex;
  align-items: center;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 4px;
}
.mainnav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 36px;
  padding: 6px 15px;
  border-radius: var(--r-pill);
  color: var(--text-muted);
  font-size: 15px;
  font-weight: 500;
  white-space: nowrap;
}
.mainnav a:hover { background: var(--bg-panel); color: var(--text); }
.mainnav a.is-current { background: var(--accent-soft); color: var(--accent); font-weight: 650; }
.header-tools { display: flex; align-items: center; gap: 10px; flex-shrink: 0; margin-left: auto; }
.language { position: relative; }
.lang {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 36px;
  padding: 8px 14px 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--r-pill);
  background: var(--bg);
  color: var(--text);
  font: 500 14px/1.2 var(--font-body);
  white-space: nowrap;
}
.lang svg { width: 16px; height: 16px; color: var(--text-muted); flex-shrink: 0; }
.lang__caret { color: var(--text-muted); font-size: 11px; }
.lang__short { display: none; }
.language-menu {
  position: absolute;
  right: 0;
  top: calc(100% + 12px);
  width: 190px;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: var(--r-float);
  background: var(--bg);
  color: var(--text);
  box-shadow: var(--shadow-float);
  z-index: 4;
}
.language-menu a {
  display: flex;
  align-items: center;
  min-height: 44px;
  padding: 10px 14px;
  color: var(--text-muted);
  border-radius: var(--r-chip);
}
.language-menu a:hover, .language-menu a[aria-current] { background: var(--accent-soft); color: var(--accent); }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  padding: 10px;
  border: 1px solid var(--border);
  border-radius: var(--r-pill);
  background: var(--bg);
  color: var(--text);
}
.menu-toggle svg { width: 22px; height: 22px; }
.mobile-drawer {
  position: absolute;
  inset: var(--nav-h) 0 auto;
  z-index: 3;
  padding: 16px var(--gutter) 24px;
  max-height: calc(100dvh - var(--nav-h));
  overflow-y: auto;
  overscroll-behavior: contain;
  background: var(--bg);
  color: var(--text);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-float);
}
.mobile-drawer ul { margin: 0; padding: 0; list-style: none; }
.mobile-drawer a {
  display: flex;
  align-items: center;
  width: 100%;
  min-height: 48px;
  padding: 12px 16px;
  color: var(--text-muted);
  border-radius: var(--r-card);
}
.mobile-drawer a:hover, .mobile-drawer a[aria-current] { background: var(--accent-soft); color: var(--accent); }
.mobile-drawer__label { padding: 20px 16px 8px; font-size: var(--text-sm); color: var(--text-muted); }
.nav-veil {
  position: fixed;
  inset: var(--nav-h) 0 0;
  z-index: 2;
  border: 0;
  padding: 0;
  background: var(--veil);
  color: var(--text);
}
.preview-mobile { display: none; }
.preview-mobile > summary { list-style: none; }
.preview-mobile > summary::-webkit-details-marker { display: none; }

.card, .panel {
  background: var(--bg);
  color: var(--text);
  border-radius: var(--r-panel);
  padding: 28px;
}
.card { box-shadow: var(--shadow-soft); }
.panel { background: var(--bg-panel); color: var(--text); }
.card h3, .panel h3 { margin-top: 0; }
.prose { min-width: 0; overflow-wrap: break-word; }
.prose p, .prose ul, .prose ol { margin-block: 20px; }
.prose li + li { margin-top: 8px; }
.prose h2 { margin-top: 64px; margin-bottom: 24px; }
.prose h3 { margin-top: 36px; margin-bottom: 16px; }
.prose :not(pre) > code {
  padding: 2px 5px;
  border-radius: var(--r-chip);
  background: var(--bg-panel);
  color: var(--text);
  font-size: .9em;
}
.prose a:not(.btn-primary):not(.btn-secondary) { text-decoration: underline; text-underline-offset: 4px; }
.decorated, .hero, [data-hero-visual], .feature-visual { overflow-x: clip; }
.reveal { opacity: 1; }
.reveal-ready .reveal:not(.shown) { opacity: 0; transform: translateY(16px); }
.reveal-ready .reveal { transition: opacity var(--reveal-time) var(--ease), transform var(--reveal-time) var(--ease); }
.reveal-ready .reveal.shown { opacity: 1; transform: none; }

.site-footer {
  margin-top: 72px;
  padding-top: 64px;
  padding-bottom: 100px;
  border-top: 1px solid var(--border);
  background: var(--bg-panel);
  color: var(--text);
}
.footer-grid { display: grid; grid-template-columns: 1.25fr .8fr 1.4fr .8fr; gap: 40px; }
.footer-brand p { max-width: 310px; margin-top: 18px; font-size: var(--text-sm); color: var(--text-muted); }
.footer-title { margin: 0 0 16px; font-size: var(--text-sm); font-weight: 750; }
.footer-links { list-style: none; margin: 0; padding: 0; }
.footer-links a { display: inline-block; padding-block: 5px; font-size: var(--text-sm); color: var(--text-muted); overflow-wrap: anywhere; }
.footer-links a:hover { color: var(--accent); }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  font-size: var(--text-sm);
  color: var(--text-muted);
}
.footer-bottom a { color: var(--text-muted); }
.footer-legal { display: flex; flex-wrap: wrap; gap: 20px; }

@media (max-width: 1280px) {
  .topbar__inner { gap: 24px; }
  .mainnav a { padding-inline: 11px; font-size: 14.5px; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .mainnav { display: none; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .menu-toggle { display: inline-flex; }
}
@media (max-width: 960px) {
  .mainnav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .preview-mobile { display: block; }
}
@media (min-width: 961px) {
  html[lang="zh-CN"] .mobile-drawer, html[lang="zh-CN"] .nav-veil,
  html[lang="zh-TW"] .mobile-drawer, html[lang="zh-TW"] .nav-veil { display: none; }
}
@media (max-width: 768px) {
  :root { --h1: 28px; --h2: 28px; --h3: 24px; --section-space: 64px; }
  .grid--3 { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  :root { --gutter: 20px; }
  .topbar__inner { gap: 8px; }
  .brand__name { font-size: 15px; }
  .brand { gap: 8px; }
  .header-tools { gap: 6px; margin-left: auto; }
  .lang__full { display: none; }
  .lang__short { display: inline; }
  .lang { padding-inline: 10px; min-height: 40px; }
  .lang svg { display: none; }
  .grid--2, .footer-grid { grid-template-columns: 1fr; }
  .card, .panel { padding: 24px; }
  .tilt, .set-card, .feature-visual::before, [data-tilt] { transform: none !important; }
  .site-footer { padding-top: 48px; }
  .footer-grid { gap: 32px; }
}
@media (max-width: 359px) {
  :root { --gutter: 16px; }
  .brand__name { font-size: 13px; }
  .brand__mark { width: 28px; height: 28px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .reveal-ready .reveal:not(.shown) { opacity: 1; transform: none; }
}