:root {
  --bg: #FFFFFF;
  --bg-panel: #F4F6F8;
  --bg-panel-2: #EBEEF1;
  --border: #E2E6EA;
  --accent: #36A3E6;
  --accent-dark: #1C7DBF;
  --text: #2C3338;
  --text-muted: #6B747C;
  --text-soft: #9AA2A9;
  --success: #2E9E6A;
  --warn: #C98A12;
  --error: #D2463C;
  --on-accent: #FFFFFF;
  --device-edge: #D7DCE1;
  --device-shade: #C3CAD1;
  --clear: transparent;
  --veil: rgba(44, 51, 56, .24);
  --floor-shade: rgba(44, 51, 56, .14);
  --ring-success: rgba(46, 158, 106, .32);
  --ring-focus: rgba(54, 163, 230, .35);
  --font-display: "Inter", "Noto Sans SC", "Noto Sans JP", "Noto Sans KR", -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Inter", "Noto Sans SC", "Noto Sans JP", "Noto Sans KR", -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --r-ctl: 6px;
  --r-card: 10px;
  --r-device: 18px;
  --r-pill: 999px;
  --r-round: 50%;
  --r-flat: 0;
  --r-base: 2px 2px 140px 140px / 2px 2px 14px 14px;
  --shadow-chip: 0 1px 2px rgba(44, 51, 56, .05), 0 6px 16px -10px rgba(44, 51, 56, .14);
  --shadow-btn: 0 1px 2px rgba(28, 125, 191, .18), 0 8px 18px -10px rgba(28, 125, 191, .45);
  --shadow-window: 0 1px 2px rgba(44, 51, 56, .06), 0 14px 30px -16px rgba(44, 51, 56, .22);
  --shadow-laptop: 0 1px 1px rgba(44, 51, 56, .04), 0 20px 40px -22px rgba(44, 51, 56, .16), 0 56px 96px -44px rgba(44, 51, 56, .20);
  --shadow-phone: 0 2px 4px rgba(44, 51, 56, .06), 0 22px 40px -14px rgba(44, 51, 56, .26), 0 64px 100px -34px rgba(44, 51, 56, .26);
  --shadow-knob: 0 1px 2px rgba(44, 51, 56, .22);
  --gutter: 32px;
  --content-width: 1120px;
  --reading-width: 760px;
  --nav-h: 68px;
  --space-section: 112px;
  --size-h1: clamp(34px, 3.4vw, 48px);
  --size-h2: clamp(28px, 3vw, 40px);
  --size-h3: 22px;
  --size-body: 16px;
  --weight-display: 900;
  --weight-bold: 700;
  --weight-medium: 600;
  --weight-normal: 400;
  --tracking-display: -.02em;
  --motion-fast: .2s;
  --motion-reveal: .65s;
}
*, *::before, *::after { box-sizing: border-box; }
html {
  background: var(--bg);
  color: var(--text);
  scroll-behavior: smooth;
  scroll-padding-top: 28px;
  -webkit-text-size-adjust: 100%;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: var(--size-body)/1.75 var(--font-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
html.nav-open { overflow: hidden; }
[hidden] { display: none !important; }
img { display: block; max-width: 100%; height: auto; }
svg { vertical-align: middle; flex-shrink: 0; }
button, input, select, textarea { font: inherit; }
button, summary { cursor: pointer; }
button { color: var(--text); }
a { color: var(--accent-dark); 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);
}
::selection { background: var(--bg-panel-2); color: var(--text); }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--text);
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 {
  margin: 0 0 24px;
  font-size: var(--size-h1);
  font-weight: var(--weight-display);
  line-height: 1.15;
  letter-spacing: var(--tracking-display);
}
h2 {
  margin: 0 0 24px;
  font-size: var(--size-h2);
  font-weight: var(--weight-display);
  line-height: 1.25;
  letter-spacing: var(--tracking-display);
}
h3 { margin: 0 0 14px; font-size: var(--size-h3); line-height: 1.4; font-weight: 800; }
h4 { margin: 0 0 12px; font-size: 18px; line-height: 1.5; }
p { margin: 0 0 20px; }
ul, ol { padding-inline-start: 1.5em; }
hr { border: 0; border-top: 1px solid var(--border); margin: 40px 0; }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; font-size: .88em; }
:not(pre) > code {
  padding: .12em .3em;
  border-radius: var(--r-ctl);
  background: var(--bg-panel);
  color: var(--text);
}
pre {
  max-width: 100%;
  min-width: 0;
  margin: 24px 0;
  padding: 24px;
  overflow-x: auto;
  overscroll-behavior-x: contain;
  background: var(--bg-panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  font-size: 13px;
  line-height: 1.8;
  tab-size: 2;
}
pre code { font-size: inherit; white-space: pre; overflow-wrap: normal; word-break: normal; }
.wrap {
  width: 100%;
  max-width: calc(var(--content-width) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
  min-width: 0;
}
.reading { max-width: calc(var(--reading-width) + var(--gutter) * 2); }
.section { padding-top: var(--space-section); padding-bottom: var(--space-section); }
.section--panel { background: var(--bg-panel); color: var(--text); }
.section--decorated, .hero { overflow-x: clip; }
.section__intro { max-width: 640px; margin-bottom: 48px; }
.section__intro p, .muted { color: var(--text-muted); }
.eyebrow { margin-bottom: 14px; color: var(--text-muted); font-size: 13px; font-weight: var(--weight-medium); }
.keep { white-space: nowrap; }
h1 .keep, h2 .keep { white-space: normal; }
.center { text-align: center; }
.mono { font-family: var(--font-mono); }
.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 > *, .split > *, .prose, .prose > *, .prose div { min-width: 0; }
.split { display: grid; grid-template-columns: 1.1fr 1fr; align-items: center; gap: 64px; }
.card, .panel {
  min-width: 0;
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  background: var(--bg);
  color: var(--text);
}
.card { box-shadow: var(--shadow-chip); }
.panel--inset { background: var(--bg-panel); color: var(--text); }
.card p:last-child, .panel p:last-child { margin-bottom: 0; }
.card__meta { color: var(--text-muted); font-size: 13px; margin-bottom: 12px; }
.prose { line-height: 1.9; overflow-wrap: break-word; }
.prose h2 { margin-top: 64px; scroll-margin-top: 28px; }
.prose h3 { margin-top: 36px; scroll-margin-top: 28px; }
.prose li { margin-bottom: 8px; }
.prose img { margin-block: 28px; }
.prose a { overflow-wrap: anywhere; }
.prose > :first-child { margin-top: 0; }
.btn {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 22px;
  border: 1px solid var(--border);
  border-radius: var(--r-ctl);
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: var(--weight-bold);
  line-height: 1.4;
  text-decoration: none;
  white-space: nowrap;
  transition: background-color var(--motion-fast), border-color var(--motion-fast), color var(--motion-fast);
}
.btn svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.btn--primary { background: var(--accent); color: var(--on-accent); border-color: var(--accent); box-shadow: var(--shadow-btn); }
.btn--primary:hover, .btn--primary.is-hover { background: var(--accent-dark); color: var(--on-accent); border-color: var(--accent-dark); }
.btn--ghost:hover, .btn--ghost.is-hover { border-color: var(--text-soft); }
.btn:active { transform: translateY(1px); }
.btn:disabled, .btn[aria-disabled="true"] { background: var(--bg-panel-2); color: var(--text-muted); border-color: var(--border); box-shadow: none; cursor: not-allowed; }
.btn.is-focus { outline: 2px solid var(--accent); outline-offset: 3px; }
.btn__arrow { color: var(--text-muted); }
.cta { display: flex; justify-content: center; flex-wrap: wrap; gap: 12px; margin: 0 0 16px; }
.text-link { color: var(--accent-dark); font-weight: var(--weight-medium); text-decoration: none; }
.text-link:hover { text-decoration: underline; }
.skip-link {
  position: fixed;
  top: 8px;
  left: 16px;
  z-index: 100;
  transform: translateY(-160%);
  padding: 10px 16px;
  border-radius: var(--r-ctl);
  background: var(--bg);
  color: var(--text);
  box-shadow: var(--shadow-window);
}
.skip-link:focus { transform: none; }
#site-header.topbar { position: relative; z-index: 100; height: var(--nav-h); background: var(--bg); color: var(--text); border-bottom: 1px solid var(--border); }
.topbar__inner {
  position: relative;
  width: 100%;
  max-width: min(100%, calc(1280px + var(--gutter) * 2));
  height: 100%;
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 28px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
  color: var(--text);
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 17px;
  letter-spacing: -.01em;
  text-decoration: none;
  white-space: nowrap;
}
.brand__mark { width: 30px; height: 30px; flex-shrink: 0; }
.desktop-nav { min-width: 0; margin-left: auto; }
.menu { display: flex; align-items: center; list-style: none; margin: 0; padding: 0; gap: 2px; }
.menu a {
  display: flex;
  align-items: center;
  gap: 7px;
  height: 36px;
  padding: 0 11px;
  color: var(--text-muted);
  border-radius: var(--r-ctl);
  font-size: 14px;
  line-height: 1.4;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--motion-fast), background-color var(--motion-fast);
}
.menu svg { width: 15px; height: 15px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
.menu a:hover { color: var(--text); background: var(--bg-panel); }
.menu a[aria-current="page"] { color: var(--text); font-weight: var(--weight-medium); }
.menu a[aria-current="page"] svg { color: var(--accent); }
.header-tools { display: flex; align-items: center; gap: 8px; flex-shrink: 0; }
.language { position: relative; }
.lang {
  display: flex;
  align-items: center;
  gap: 7px;
  min-height: 34px;
  padding: 0 12px;
  border: 1px solid var(--border);
  border-radius: var(--r-ctl);
  background: var(--bg);
  color: var(--text);
  font: 13px/1.4 var(--font-body);
  white-space: nowrap;
}
.lang svg { width: 14px; height: 14px; fill: none; stroke: var(--text-muted); stroke-width: 1.6; stroke-linecap: round; }
.lang__caret { color: var(--text-muted); font-size: 11px; }
.lang__short { display: none; }
.language__list {
  position: absolute;
  z-index: 3;
  top: calc(100% + 8px);
  right: 0;
  width: 180px;
  padding: 6px;
  margin: 0;
  list-style: none;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  box-shadow: var(--shadow-window);
}
.language__list a { display: flex; align-items: center; min-height: 44px; padding: 8px 12px; color: var(--text); text-decoration: none; border-radius: var(--r-ctl); }
.language__list a:hover, .language__list a[aria-current] { background: var(--bg-panel); color: var(--text); }
.menu-toggle { 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-toggle svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; }
.mobile-nav { display: none; }
.menu-veil { position: fixed; inset: var(--nav-h) 0 0; z-index: 40; border: 0; background: var(--veil); color: var(--text); }
.site-footer { padding-top: 72px; padding-bottom: 28px; border-top: 1px solid var(--border); background: var(--bg-panel); color: var(--text); }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1.25fr 1fr; gap: 40px; }
.footer-grid > * { min-width: 0; }
.footer-brand p { max-width: 300px; margin-top: 20px; color: var(--text-muted); font-size: 14px; }
.footer-title { font-size: 14px; font-weight: var(--weight-bold); margin: 0 0 16px; }
.footer-links { margin: 0; padding: 0; list-style: none; }
.footer-links li { margin-bottom: 8px; }
.footer-links a { color: var(--text-muted); font-size: 14px; text-decoration: none; overflow-wrap: anywhere; }
.footer-links a:hover { color: var(--text); text-decoration: underline; }
.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: 12px; color: var(--text-muted); }
.footer-bottom a { color: var(--text-muted); margin-inline-start: 16px; }
.reveal { opacity: 1; transform: none; }
html.reveal-ready .reveal:not(.shown) { opacity: 0; transform: translateY(18px); }
html.reveal-ready .reveal { transition: opacity var(--motion-reveal) ease, transform var(--motion-reveal) ease; }
@media (max-width: 1280px) {
  .topbar__inner { gap: 18px; }
  .menu a { padding-inline: 8px; gap: 6px; font-size: 13px; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .desktop-nav { display: none; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .menu-toggle { display: flex; }
  html:not([lang="zh-CN"]):not([lang="zh-TW"]) .header-tools { margin-left: auto; }
  #site-header .mobile-nav:not([hidden]) {
    display: block;
    position: fixed;
    top: var(--nav-h);
    left: 0;
    right: 0;
    z-index: 101;
    max-height: calc(100dvh - var(--nav-h));
    overflow-y: auto;
    overscroll-behavior: contain;
    padding: 4px var(--gutter);
    border-bottom: 1px solid var(--border);
    background: var(--bg);
    color: var(--text);
    box-shadow: var(--shadow-window);
  }
  .mobile-nav ul { list-style: none; padding: 0; margin: 0; }
  .mobile-nav a { display: flex; align-items: center; gap: 12px; width: 100%; min-height: 44px; padding: 6px 12px; color: var(--text); text-decoration: none; border-radius: var(--r-ctl); }
  .mobile-nav a:hover, .mobile-nav a[aria-current] { background: var(--bg-panel); color: var(--text); }
  .mobile-nav svg { width: 18px; height: 18px; fill: none; stroke: currentColor; stroke-width: 1.6; stroke-linecap: round; stroke-linejoin: round; }
  .mobile-nav__languages { margin-top: 8px !important; padding-top: 8px !important; border-top: 1px solid var(--border); }
}
@media (max-width: 1100px) {
  .desktop-nav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: flex; }
  .split { gap: 36px; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 768px) {
  :root { --gutter: 20px; --space-section: 72px; --size-h1: clamp(24px, 6vw, 30px); --size-h2: 28px; }
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .split { grid-template-columns: minmax(0, 1fr); gap: 32px; }
}
@media (max-width: 640px) {
  :root { --gutter: 16px; }
  .grid--2, .grid--3 { grid-template-columns: minmax(0, 1fr); }
  .card, .panel { padding: 22px; }
  .brand { font-size: 15px; gap: 8px; }
  .brand__mark { width: 28px; height: 28px; }
  .topbar__inner { gap: 8px; }
  .header-tools { margin-left: auto; gap: 6px; }
  .lang { padding-inline: 10px; min-height: 44px; }
  .lang__full { display: none; }
  .lang__short { display: inline; }
  .lang > svg { display: none; }
  .footer-grid { gap: 32px 20px; }
  .footer-brand { grid-column: 1 / -1; }
  .footer-bottom { flex-direction: column; }
  .footer-bottom a { margin-inline: 0 16px; }
  .tilt, [data-tilt] { transform: none !important; }
  pre { padding: 18px; }
}
@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; }
}