:root {
  color-scheme: light;
  --bg: #FCFCFC;
  --panel: #FFFFFF;
  --layer: #F2F2F4;
  --border: #E2E2E7;
  --accent: #C52BD4;
  --accent-dark: #9520A1;
  --ink: #202024;
  --muted: #65656E;
  --green: #12996E;
  --yellow: #EFAD16;
  --error: #D8483D;
  --tint: #FAEFFB;
  --tint-edge: #EEDAF1;
  --tint-line: #F2E6F4;
  --subtle: #94949E;
  --chrome-dot: #D5D5DC;
  --flag-white: #FFFFFF;
  --flag-red: #DE2338;
  --flag-us-red: #B22234;
  --flag-us-blue: #3C3B6E;
  --flag-uk-blue: #012169;
  --flag-uk-red: #C8102E;
  --flag-hk-red: #DE2910;
  --flag-sg-red: #EF3340;
  --veil: #20202460;
  --clear: transparent;
  --display: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', system-ui, sans-serif;
  --body: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', system-ui, sans-serif;
  --mono: 'JetBrains Mono', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', monospace;
  --text-xs: 11px;
  --text-sm: 12px;
  --text-note: 13px;
  --text-nav: 14px;
  --text-base: 15px;
  --text-md: 16px;
  --text-lg: 18px;
  --text-card: 22px;
  --text-brand: 25px;
  --text-section: 26px;
  --text-h2: 36px;
  --text-display: 64px;
  --text-display-mid: 52px;
  --text-mobile: 36px;
  --regular: 400;
  --medium: 500;
  --semibold: 600;
  --bold: 700;
  --black: 900;
  --round: 24px;
  --round-sm: 14px;
  --round-xs: 6px;
  --round-logo: 12px;
  --round-glyph: 3px;
  --pill: 999px;
  --circle: 50%;
  --shadow-window: 0 30px 64px -26px #20202430, 0 8px 20px -9px #20202420, 0 1px 3px #2020240D;
  --shadow-page: 0 12px 30px -16px #2020242B;
  --shadow-button: 0 8px 20px -9px #C52BD460;
  --shadow-small: 0 5px 20px #20202408;
  --highlight: inset 0 1px 0 #FFFFFF;
  --tracking-title: -0.02em;
  --tracking-brand: -0.8px;
  --tracking-card: -0.5px;
  --tracking-label: 1.8px;
  --leading-body: 1.8;
  --leading-heading: 1.25;
  --leading-display: 1.15;
  --gutter: 24px;
  --content-width: 1268px;
  --reading-width: 780px;
  --section-space: 72px;
  --anchor-offset: 24px;
  --toc-top: 12px;
  --toc-offset: 104px;
  --touch: 44px;
  --focus-width: 3px;
  --duration: 180ms;
  --reveal-duration: 600ms;
  --ease: cubic-bezier(.2, .7, .2, 1);
}

*,
*::before,
*::after { box-sizing: border-box; }
html {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--body);
  -webkit-font-smoothing: antialiased;
  scroll-padding-top: var(--anchor-offset);
  scroll-behavior: smooth;
}
body { margin: 0; font-size: var(--text-base); line-height: var(--leading-body); }
html.nav-open { overflow: hidden; }
main, article, section, aside, nav, div, figure { min-width: 0; }
img { display: block; max-width: 100%; height: auto; }
svg { display: block; flex-shrink: 0; }
button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
a { color: inherit; text-decoration: none; }
a, button, summary { -webkit-tap-highlight-color: var(--tint-edge); }
:where(a, button, summary, input, select, textarea, [tabindex]):focus-visible {
  outline: var(--focus-width) solid var(--accent-dark);
  outline-offset: 4px;
}
[hidden] { display: none !important; }
h1, h2, h3, h4 { font-family: var(--display); color: var(--ink); }
h1 {
  font-size: var(--text-display);
  font-weight: var(--black);
  line-height: var(--leading-display);
  letter-spacing: var(--tracking-title);
  margin: 0;
}
h2 {
  font-size: var(--text-h2);
  font-weight: var(--black);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-title);
  margin: 0 0 24px;
  text-wrap: balance;
}
h3 { font-size: var(--text-card); font-weight: var(--bold); line-height: 1.4; margin: 0 0 16px; }
p { margin: 0 0 20px; }
ul, ol { padding-inline-start: 24px; }
strong { font-weight: var(--bold); }
small { font-size: var(--text-sm); }
code {
  font-family: var(--mono);
  font-size: .9em;
  overflow-wrap: anywhere;
  background: var(--layer);
  border-radius: var(--round-xs);
  padding: 2px 5px;
}
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 20px;
  background: var(--layer);
  border: 1px solid var(--border);
  border-radius: var(--round-sm);
  font-family: var(--mono);
}
pre code { padding: 0; overflow-wrap: normal; white-space: pre; }
hr { border: 0; border-top: 1px solid var(--border); margin: 32px 0; }
.no-break { white-space: nowrap; }
.muted { color: var(--muted); }
.mono { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.wrap { width: 100%; max-width: var(--content-width); margin-inline: auto; padding-inline: var(--gutter); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.reading { max-width: var(--reading-width); margin-inline: auto; }
.prose { overflow-wrap: anywhere; }
.prose h2 { margin-top: 48px; }
.prose h3 { margin-top: 32px; }
.prose a:not(.action) { color: var(--accent-dark); text-decoration: underline; text-underline-offset: 4px; }
.prose li + li { margin-top: 8px; }
.panel, .card {
  padding: 28px;
  border: 1px solid var(--border);
  border-radius: var(--round);
  background: var(--panel);
  box-shadow: var(--shadow-small), var(--highlight);
}
.stack { display: grid; gap: 24px; }
.cluster { display: flex; align-items: center; flex-wrap: wrap; gap: 12px; }
.symbol-library { position: absolute; width: 0; height: 0; overflow: hidden; }
.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;
  left: var(--gutter);
  top: 8px;
  z-index: 60;
  transform: translateY(-180%);
  padding: 10px 18px;
  background: var(--panel);
  border-radius: var(--pill);
  box-shadow: var(--shadow-small);
}
.skip-link:focus { transform: none; }

.action, .btn-primary {
  min-height: 56px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 25px;
  padding: 12px 27px;
  border: 1px solid var(--clear);
  border-radius: var(--pill);
  font-size: var(--text-md);
  font-weight: var(--bold);
  line-height: 1.4;
  text-align: center;
  transition: background var(--duration), border-color var(--duration), color var(--duration);
}
.action svg { width: 19px; height: 19px; }
.action-primary, .btn-primary {
  background: var(--accent);
  color: var(--panel);
  box-shadow: var(--shadow-button);
}
.action-primary:hover, .btn-primary:hover, .action-primary.is-hover { background: var(--accent-dark); }
.action-primary:active, .btn-primary:active, .action-primary.is-active { background: var(--accent-dark); box-shadow: var(--highlight); }
.action-secondary { background: var(--layer); color: var(--ink); padding-inline: 29px; }
.action-secondary:hover { background: var(--border); }
.action-outline { border-color: var(--border); background: var(--panel); }
.action-outline:hover { border-color: var(--accent-dark); color: var(--accent-dark); }
.action:disabled, .action[aria-disabled="true"] { background: var(--layer); color: var(--muted); box-shadow: none; cursor: not-allowed; }
.action.is-focus { outline: var(--focus-width) solid var(--accent-dark); outline-offset: 4px; }
.text-link { display: inline-flex; align-items: center; min-height: 24px; color: var(--accent-dark); gap: 8px; }
.text-link:hover { text-decoration: underline; text-underline-offset: 4px; }

#site-header { position: relative; z-index: 30; }
.site-head {
  height: 94px;
  max-width: 1360px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 32px;
  position: relative;
  z-index: 30;
  line-height: 1.5;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  flex-shrink: 0;
  font-size: var(--text-brand);
  font-weight: var(--black);
  letter-spacing: var(--tracking-brand);
}
.brand-mark { width: 40px; height: 40px; flex-shrink: 0; }
.brand-zh { font-weight: var(--medium); color: var(--muted); font-size: var(--text-md); }
.primary-nav { display: flex; align-items: center; justify-content: center; gap: 3px; flex: 1; white-space: nowrap; }
.primary-nav a {
  font-size: var(--text-nav);
  font-weight: var(--medium);
  color: var(--muted);
  padding: 11px 12px;
  border-radius: var(--pill);
}
.primary-nav a[aria-current="page"], .drawer a[aria-current="page"] {
  background: var(--layer);
  color: var(--ink);
  font-weight: var(--bold);
}
.primary-nav a:hover { color: var(--ink); background: var(--layer); }
.account-tools { display: flex; align-items: center; gap: 19px; white-space: nowrap; font-size: var(--text-nav); }
.login {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: var(--touch);
  padding: 10px 22px;
  border: 1px solid var(--border);
  border-radius: var(--pill);
  background: var(--panel);
  font-weight: var(--semibold);
}
.login:hover { border-color: var(--subtle); }
.language { position: relative; color: var(--muted); font-size: var(--text-note); }
.language-toggle, .language > summary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: var(--touch);
  padding: 4px;
  border: 0;
  background: var(--clear);
  cursor: pointer;
  list-style: none;
}
.language > summary::-webkit-details-marker { display: none; }
.language-toggle span { font-size: var(--text-xs); }
.language-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 176px;
  padding: 8px;
  border: 1px solid var(--border);
  border-radius: var(--round-sm);
  background: var(--panel);
  box-shadow: var(--shadow-page);
  z-index: 35;
}
.language-menu a { display: flex; align-items: center; min-height: var(--touch); padding: 8px 12px; border-radius: var(--round-xs); }
.language-menu a:hover, .language-menu a[aria-current="true"] { color: var(--accent-dark); background: var(--tint); }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  min-width: var(--touch);
  min-height: var(--touch);
  padding: 10px;
  border: 1px solid var(--border);
  border-radius: var(--pill);
  background: var(--panel);
}
.menu-toggle svg { width: 21px; height: 21px; }
.drawer {
  position: absolute;
  inset: 100% var(--gutter) auto;
  z-index: 34;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: var(--round);
  background: var(--panel);
  box-shadow: var(--shadow-window);
  max-height: calc(100dvh - 102px);
  overflow-y: auto;
  overscroll-behavior: contain;
}
.drawer a { display: flex; width: 100%; align-items: center; min-height: 44px; padding: 12px 16px; border-radius: var(--round-sm); }
.drawer a:hover { background: var(--tint); color: var(--accent-dark); }
.drawer-label { display: block; margin: 12px 16px 6px; color: var(--muted); font-size: var(--text-sm); }
.nav-veil { position: fixed; inset: 0; z-index: 20; background: var(--veil); border: 0; width: 100%; height: 100%; padding: 0; }

.site-footer { margin-top: 48px; background: var(--layer); border-top: 1px solid var(--border); }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr .9fr; gap: 40px; padding-top: 48px; padding-bottom: 36px; }
.footer-brand p { color: var(--muted); margin-top: 20px; max-width: 320px; }
.footer-heading { font-size: var(--text-nav); font-weight: var(--bold); margin: 0 0 16px; }
.footer-links { display: grid; align-content: start; gap: 6px; }
.footer-links a { color: var(--muted); font-size: var(--text-nav); min-height: 28px; padding-block: 3px; }
.footer-links a:hover { color: var(--accent-dark); }
.footer-base { padding-top: 22px; padding-bottom: 26px; border-top: 1px solid var(--border); display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px 24px; font-size: var(--text-note); color: var(--muted); }
.footer-legal { display: flex; gap: 20px; flex-wrap: wrap; }
.footer-legal a { min-height: 24px; }

.reveal { transition: opacity var(--reveal-duration) var(--ease), transform var(--reveal-duration) var(--ease); }
.reveal.pending { opacity: 0; transform: translateY(16px); }
.reveal.shown { opacity: 1; transform: none; }
.decor-section { position: relative; overflow-x: clip; }
.tilt-decor { transform: rotate(-3deg); }
@media (max-width: 1250px) {
  .site-head { gap: 18px; padding-inline: 28px; }
  .primary-nav { gap: 0; }
  .primary-nav a { padding: 10px 8px; font-size: var(--text-note); }
  .account-tools { gap: 13px; }
  .brand { font-size: var(--text-card); }
  .brand-mark { width: 34px; height: 34px; }
}
@media (max-width: 1050px) {
  .site-head { height: auto; min-height: 90px; flex-wrap: wrap; padding-block: 20px 16px; gap: 15px; }
  .primary-nav { order: 3; flex-basis: 100%; justify-content: space-between; }
  .account-tools { margin-left: auto; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 780px) {
  :root { --section-space: 48px; --text-h2: 28px; }
  h1 { font-size: var(--text-mobile); }
  .site-head { padding: 18px 20px 12px; min-height: 80px; gap: 10px; flex-wrap: nowrap; }
  .primary-nav { display: none; }
  .account-tools { margin-left: auto; gap: 8px; }
  .login { padding: 8px 17px; }
  .language { font-size: var(--text-sm); }
  .menu-toggle { display: inline-flex; }
  .action { min-height: 52px; padding-inline: 24px; font-size: var(--text-base); }
  .preview-head { flex-wrap: wrap; }
  .preview-head .primary-nav { display: flex; justify-content: flex-start; overflow-x: auto; padding-bottom: 3px; }
  .preview-head .primary-nav a { padding: 10px 12px; }
}
@media (max-width: 640px) {
  :root { --gutter: 20px; }
  .tilt-decor, [data-tilt] { transform: none; }
  .panel, .card { padding: 22px; }
  .footer-grid { gap: 28px; }
  .footer-brand { grid-column: 1 / -1; }
  .footer-base { flex-direction: column; }
  .brand { gap: 7px; font-size: var(--text-lg); }
  .brand-mark { width: 31px; height: 31px; }
}
@media (max-width: 370px) {
  :root { --gutter: 17px; }
  .site-head { padding-inline: 16px; gap: 6px; }
  .account-tools { gap: 5px; }
  .login { padding-inline: 12px; }
  .language-toggle { gap: 3px; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal, .reveal.pending, .reveal.shown { opacity: 1; transform: none; transition: none; }
  .action, .btn-primary { transition: none; }
}