:root {
  --c-bg: #FFFFFF;
  --c-panel: #F7F7F9;
  --c-panel-2: #F1F2FC;
  --c-panel-active: #ECEDF1;
  --c-border: #E6E7EB;
  --c-border-soft: #EFF0F3;
  --c-accent: #5561E0;
  --c-accent-dark: #3B45B8;
  --c-accent-tint: rgba(85, 97, 224, .08);
  --c-accent-ring: rgba(85, 97, 224, .35);
  --c-text: #1B1C1F;
  --c-text-muted: #6B6F7A;
  --c-text-faint: #A3A6AF;
  --c-on-ink: #FFFFFF;
  --c-ink-hover: #2E3036;
  --c-success: #1F9D6B;
  --c-success-tint: rgba(31, 157, 107, .16);
  --c-warn: #C98410;
  --c-error: #D9443A;
  --c-glow-a: #C9CEFB;
  --c-glow-b: #E3DCFA;
  --c-clear: transparent;
  --c-veil: rgba(27, 28, 31, .28);
  --font-display: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans", "Apple SD Gothic Neo", "Malgun Gothic", "Microsoft YaHei", system-ui, sans-serif;
  --font-body: "Inter", "Noto Sans SC", "PingFang SC", "Hiragino Sans", "Apple SD Gothic Neo", "Malgun Gothic", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --weight-normal: 400;
  --weight-title: 500;
  --weight-strong: 600;
  --r-pill: 999px;
  --r-card: 24px;
  --r-card-small: 20px;
  --r-pop: 16px;
  --r-item: 8px;
  --r-key: 5px;
  --r-dot: 50%;
  --r-caret: 1px;
  --r-bar: 2px;
  --shadow-xs: 0 1px 2px rgba(27, 28, 31, .05);
  --shadow-btn: 0 1px 2px rgba(27, 28, 31, .18), inset 0 1px 0 rgba(255, 255, 255, .10);
  --shadow-card: 0 1px 2px rgba(27, 28, 31, .03), 0 18px 44px -18px rgba(27, 28, 31, .09);
  --shadow-float: 0 1px 1px rgba(27, 28, 31, .03), 0 18px 44px -14px rgba(27, 28, 31, .12), 0 60px 120px -40px rgba(59, 69, 184, .24);
  --shadow-pop: 0 2px 4px rgba(27, 28, 31, .04), 0 22px 48px -12px rgba(27, 28, 31, .18), 0 40px 90px -30px rgba(59, 69, 184, .26);
  --nav-h: 64px;
  --peek: 28px;
  --device-w: 1120px;
  --content-w: 1120px;
  --reading-w: 800px;
  --header-w: 1280px;
  --gutter: 32px;
  --section-space: 96px;
  --ease: cubic-bezier(.2, .7, .2, 1);
  --duration-fast: .18s;
  --duration-reveal: .55s;
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 88px; }
html.nav-open { overflow: hidden; }
body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-text);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
[hidden] { display: none !important; }
img, svg { max-width: 100%; vertical-align: middle; }
img { height: auto; }
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font: inherit; }
button, summary, a { -webkit-tap-highlight-color: var(--c-clear); }
button { cursor: pointer; }
button, a { touch-action: manipulation; }
button:disabled { cursor: not-allowed; }
:focus-visible { outline: 2px solid var(--c-accent); outline-offset: 3px; border-radius: var(--r-item); }
::selection { background: var(--c-accent-tint); color: var(--c-text); }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: var(--weight-title);
  letter-spacing: -.02em;
  line-height: 1.25;
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 { font-size: clamp(34px, 3.4vw, 48px); }
h2 { font-size: clamp(26px, 2.6vw, 36px); }
h3 { font-size: 22px; }
p { margin: 0 0 1em; }
strong { font-weight: var(--weight-strong); }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; }
pre {
  min-width: 0;
  max-width: 100%;
  overflow-x: auto;
  padding: 20px;
  border: 1px solid var(--c-border);
  border-radius: var(--r-pop);
  background: var(--c-panel);
  color: var(--c-text);
  font-size: 13px;
  line-height: 1.8;
  tab-size: 2;
}
pre code { overflow-wrap: normal; word-break: normal; white-space: pre; }
ul, ol { padding-left: 1.5em; }
.wrap {
  width: 100%;
  max-width: calc(var(--content-w) + var(--gutter) * 2);
  padding-inline: var(--gutter);
  margin-inline: auto;
}
.reading { max-width: calc(var(--reading-w) + var(--gutter) * 2); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-head { margin-bottom: 32px; max-width: 720px; }
.section-head h2 { margin: 8px 0 14px; }
.eyebrow { font-family: var(--font-mono); font-size: 12px; color: var(--c-text-muted); letter-spacing: .02em; }
.muted { color: var(--c-text-muted); }
.keep { white-space: nowrap; }
.text-link, .prose a:not(.btn) { color: var(--c-accent); text-decoration: underline; text-underline-offset: 4px; }
.text-link:hover, .prose a:not(.btn):hover { color: var(--c-accent-dark); }
.prose { min-width: 0; font-size: 16px; line-height: 1.9; }
.prose :is(h2, h3) { scroll-margin-top: 88px; margin-top: 2.2em; }
.prose :is(p, li) { overflow-wrap: break-word; }
.prose > :first-child { margin-top: 0; }
.prose :is(div, section, article) { min-width: 0; max-width: 100%; }
.grid { display: grid; gap: 24px; }
.grid > *, .topbar-row > *, .footer-grid > *, .feature-browser > * { min-width: 0; }
.grid-two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.card, .panel {
  min-width: 0;
  padding: 28px;
  background: var(--c-bg);
  color: var(--c-text);
  border: 1px solid var(--c-border);
  border-radius: var(--r-card);
  box-shadow: var(--shadow-card);
}
.panel { background: var(--c-panel); color: var(--c-text); box-shadow: none; }
.card h3 { margin: 0 0 12px; }
.card p:last-child { margin-bottom: 0; }
.gradient-section {
  position: relative;
  overflow-x: clip;
  background: linear-gradient(180deg, var(--c-bg), var(--c-panel-2));
  color: var(--c-text);
}
.decorated { position: relative; overflow-x: clip; }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 10px 22px;
  border: 1px solid var(--c-clear);
  border-radius: var(--r-pill);
  font-family: var(--font-body);
  font-size: 14.5px;
  font-weight: var(--weight-title);
  line-height: 22px;
  letter-spacing: -.005em;
  text-align: center;
  transition: background-color var(--duration-fast), border-color var(--duration-fast), transform var(--duration-fast);
}
.btn svg { width: 15px; height: 15px; flex-shrink: 0; }
.btn-ink { background: var(--c-text); color: var(--c-on-ink); box-shadow: var(--shadow-btn); }
.btn-ink:hover, .btn-ink.is-hover { background: var(--c-ink-hover); color: var(--c-on-ink); transform: translateY(-1px); }
.btn-line { background: var(--c-bg); color: var(--c-text); border-color: var(--c-border); box-shadow: var(--shadow-xs); }
.btn-line:hover, .btn-line.is-hover { border-color: var(--c-text-faint); transform: translateY(-1px); }
.btn:active, .btn.is-active { transform: translateY(1px); }
.btn:disabled, .btn[aria-disabled="true"] { background: var(--c-panel); color: var(--c-text-muted); box-shadow: none; border-color: var(--c-border); transform: none; }
.btn.is-focus { outline: 2px solid var(--c-accent); outline-offset: 3px; }
.button-row { display: flex; align-items: center; flex-wrap: wrap; gap: 12px; }
.topbar { height: var(--nav-h); border-bottom: 1px solid var(--c-border); background: var(--c-bg); color: var(--c-text); position: relative; z-index: 50; }
.topbar-row {
  height: 100%;
  max-width: min(100%, calc(var(--header-w) + var(--gutter) * 2));
  margin: 0 auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 40px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-weight: var(--weight-strong);
  font-size: 16px;
  letter-spacing: -.01em;
  color: var(--c-text);
  flex-shrink: 0;
}
.brand-mark { width: 30px; height: 30px; display: block; flex-shrink: 0; }
.primary-nav { margin-left: auto; min-width: 0; }
.primary-nav ul { display: flex; align-items: center; gap: 30px; list-style: none; margin: 0; padding: 0; }
.primary-nav a { font-size: 14px; font-weight: var(--weight-normal); color: var(--c-text-muted); white-space: nowrap; transition: color var(--duration-fast); }
.primary-nav a:hover { color: var(--c-text); }
.primary-nav a[aria-current="page"] { color: var(--c-text); font-weight: var(--weight-strong); }
.header-tools { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.language-box { position: relative; }
.lang {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: 34px;
  padding: 7px 14px;
  border: 1px solid var(--c-border);
  border-radius: var(--r-pill);
  background: var(--c-bg);
  color: var(--c-text);
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: var(--weight-title);
  line-height: 18px;
  white-space: nowrap;
  box-shadow: var(--shadow-xs);
}
.lang-caret { color: var(--c-text-muted); font-size: 11px; }
.lang-short { display: none; }
.language-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: 190px;
  padding: 6px;
  margin: 0;
  list-style: none;
  border: 1px solid var(--c-border);
  border-radius: var(--r-pop);
  background: var(--c-bg);
  color: var(--c-text);
  box-shadow: var(--shadow-pop);
}
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 10px 14px; border-radius: var(--r-item); }
.language-menu a:hover, .language-menu a[aria-current] { background: var(--c-panel); color: var(--c-text); }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  border: 1px solid var(--c-border);
  border-radius: var(--r-item);
  background: var(--c-bg);
  color: var(--c-text);
}
.menu-toggle svg { width: 20px; height: 20px; flex-shrink: 0; }
.mobile-nav { position: absolute; top: var(--nav-h); left: 0; right: 0; padding: 16px var(--gutter) 24px; max-height: calc(100dvh - var(--nav-h)); overflow-y: auto; overscroll-behavior: contain; background: var(--c-bg); color: var(--c-text); border-bottom: 1px solid var(--c-border); box-shadow: var(--shadow-card); z-index: 2; }
.mobile-nav ul { list-style: none; padding: 0; margin: 0; }
.mobile-nav a { display: flex; align-items: center; width: 100%; min-height: 44px; padding: 11px 12px; color: var(--c-text-muted); border-radius: var(--r-item); }
.mobile-nav a[aria-current="page"] { color: var(--c-text); font-weight: var(--weight-strong); }
.mobile-nav a:hover { background: var(--c-panel); color: var(--c-text); }
.mobile-language-label { display: block; padding: 18px 12px 8px; border-top: 1px solid var(--c-border); margin-top: 12px; font-size: 12px; color: var(--c-text-muted); }
.nav-veil { position: fixed; inset: var(--nav-h) 0 0; background: var(--c-veil); color: var(--c-text); border: 0; z-index: 1; cursor: default; }
.skip-link { position: fixed; top: -100px; left: 16px; z-index: 100; padding: 12px 18px; border-radius: var(--r-item); background: var(--c-text); color: var(--c-on-ink); }
.skip-link:focus { top: 8px; }
.site-footer { background: var(--c-panel); color: var(--c-text); border-top: 1px solid var(--c-border); padding-top: 64px; padding-bottom: 28px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1.3fr 1fr; gap: 40px; }
.footer-brand p { margin-top: 18px; max-width: 290px; color: var(--c-text-muted); font-size: 14px; }
.footer-heading { margin: 0 0 18px; font-size: 13px; font-weight: var(--weight-strong); }
.footer-links { margin: 0; padding: 0; list-style: none; }
.footer-links a { display: inline-block; padding-block: 5px; font-size: 13px; color: var(--c-text-muted); overflow-wrap: anywhere; }
.footer-links a:hover { color: var(--c-accent); }
.footer-links a[aria-current] { color: var(--c-text); font-weight: var(--weight-title); }
.footer-bottom { margin-top: 48px; padding-top: 22px; border-top: 1px solid var(--c-border); font-size: 12px; color: var(--c-text-muted); }
.reveal { opacity: 1; transform: none; }
html.reveal-ready .reveal:not(.shown) { opacity: 0; transform: translateY(16px); }
.reveal { transition: opacity var(--duration-reveal) var(--ease), transform var(--duration-reveal) var(--ease); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
@media (max-width: 1280px) {
  .topbar-row { gap: 24px; }
  .primary-nav ul { gap: 20px; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .primary-nav { display: none; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .menu-toggle { display: inline-flex; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .header-tools { margin-left: auto; }
}
@media (max-width: 1080px) {
  .primary-nav { display: none; }
  .menu-toggle { display: inline-flex; }
  .header-tools { margin-left: auto; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 768px) {
  :root { --gutter: 24px; --section-space: 64px; }
  h1 { font-size: clamp(24px, 4vw, 30px); }
  .grid-three { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  :root { --gutter: 16px; --section-space: 48px; }
  .topbar-row { gap: 12px; }
  .brand { font-size: 14px; gap: 8px; }
  .header-tools { margin-left: auto; gap: 8px; }
  .lang { padding-inline: 11px; }
  .lang-long { display: none; }
  .lang-short { display: inline; }
  .grid-two { grid-template-columns: 1fr; }
  .card, .panel { padding: 22px; }
  .footer-grid { gap: 28px 20px; }
  .footer-brand { grid-column: 1 / -1; }
  .tilt, [data-tilt] { transform: none !important; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  html.reveal-ready .reveal:not(.shown) { opacity: 1; transform: none; }
}
@media print {
  .topbar, .dl-fab, .nav-veil { display: none !important; }
  .reveal { opacity: 1 !important; transform: none !important; }
}