:root {
  --bg: #F5F8FE;
  --bg-panel: #FFFFFF;
  --bg-panel-2: #EDF1F8;
  --border: #DCE2EC;
  --line-strong: #C5CEDB;
  --accent: #1E6AD2;
  --accent-dark: #154E9E;
  --accent-soft: #E6EEFA;
  --text: #1F2A33;
  --text-muted: #5A6672;
  --success: #2F9E5B;
  --warn: #B7791F;
  --error: #C8372D;
  --mark: #FFE45C;
  --on-accent: #FFFFFF;
  --clear: transparent;
  --veil: rgba(31, 42, 51, .28);
  --font-display: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans', 'Apple SD Gothic Neo', 'Microsoft YaHei', system-ui, sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans', 'Malgun Gothic', 'Microsoft YaHei', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, 'SFMono-Regular', Menlo, Consolas, monospace;
  --r-ctl: 4px;
  --r-card: 6px;
  --r-panel: 8px;
  --r-pill: 999px;
  --r-dot: 50%;
  --r-tab: 3px 3px 0 0;
  --r-check: 3px;
  --shadow-panel: 0 1px 2px rgba(31,42,51,.04), 0 10px 24px rgba(36,66,112,.06), 0 28px 64px rgba(36,66,112,.11);
  --shadow-card: 0 1px 2px rgba(31,42,51,.04), 0 24px 60px rgba(36,66,112,.035);
  --shadow-btn: 0 1px 0 rgba(21,78,158,.35), 0 6px 16px rgba(30,106,210,.22);
  --shadow-switch: 0 1px 2px rgba(31,42,51,.2);
  --focus-ring: 0 0 0 3px var(--accent-soft);
  --wrap: 1344px;
  --reading: 860px;
  --header-content: 1280px;
  --gutter: 48px;
  --nav-h: 64px;
  --section-space: 80px;
  --space-card: 24px;
  --text-xs: 12px;
  --text-sm: 14px;
  --text-base: 16px;
  --text-lead: 20px;
  --title-xl: clamp(34px, 3.4vw, 48px);
  --title-lg: clamp(28px, 3vw, 40px);
  --title-md: 24px;
  --weight-body: 400;
  --weight-medium: 500;
  --weight-bold: 700;
  --weight-heavy: 900;
  --ease: .15s ease;
  --reveal-time: .5s;
  --header-z: 50;
  --veil-z: 40;
  --float-z: 30;
}
*, *::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(--text-base);
  line-height: 1.6;
  font-weight: var(--weight-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
[hidden] { display: none !important; }
img, svg { max-width: 100%; vertical-align: middle; }
img { height: auto; }
svg, .dot, .icon { flex-shrink: 0; }
button, input, select, textarea { font: inherit; }
button, summary { cursor: pointer; }
button { color: var(--text); }
a { color: var(--accent); text-underline-offset: .2em; }
a:hover { color: var(--accent-dark); }
button:focus-visible, a:focus-visible, summary:focus-visible, input:focus-visible, select:focus-visible, [tabindex]:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  box-shadow: var(--focus-ring);
}
button:disabled, .btn[aria-disabled="true"] { cursor: not-allowed; }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: var(--weight-heavy);
  line-height: 1.2;
  letter-spacing: -.02em;
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 { font-size: var(--title-xl); line-height: 1.14; }
h2 { font-size: var(--title-lg); }
h3 { font-size: var(--title-md); }
p { margin-top: 0; }
code { font-family: var(--font-mono); overflow-wrap: anywhere; }
pre {
  max-width: 100%;
  min-width: 0;
  margin: 0;
  padding: 20px;
  overflow-x: auto;
  background: var(--bg-panel-2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.8;
  overscroll-behavior-inline: contain;
}
pre code { overflow-wrap: normal; word-break: normal; white-space: pre; }
hr { border: 0; border-top: 1px solid var(--border); margin-block: 32px; }
::selection { background: var(--mark); color: var(--text); }
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.reading { max-width: var(--reading); margin-inline: auto; }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-heading { margin: 0 0 28px; }
.section-intro { max-width: 46em; color: var(--text-muted); }
.nowrap { white-space: nowrap; }
.muted { color: var(--text-muted); }
.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;
}
.grid { display: grid; gap: 24px; }
.grid > *, .split > *, .hero .wrap > *, .footer-grid > * { min-width: 0; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.split { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 2fr); gap: 64px; align-items: start; }
.sticky-heading { position: sticky; top: 24px; margin-top: 0; }
.prose { min-width: 0; }
.prose p, .prose li { line-height: 1.9; }
.prose p { margin-bottom: 1.3em; }
.prose h2 { margin-top: 2em; margin-bottom: .8em; }
.prose h3 { margin-top: 1.5em; }
.prose :not(pre) > code { background: var(--bg-panel-2); color: var(--accent-dark); padding: .12em .3em; border-radius: var(--r-ctl); }
.prose img { max-width: 100%; }
.prose > :first-child { margin-top: 0; }
.hl {
  background: linear-gradient(var(--clear) 56%, var(--mark) 56%, var(--mark) 92%, var(--clear) 92%);
  color: var(--text);
  padding: 0 .06em;
  margin: 0 -.03em;
  -webkit-box-decoration-break: clone;
  box-decoration-break: clone;
}
.wave-link {
  color: var(--accent);
  font-weight: var(--weight-bold);
  text-decoration: underline wavy var(--mark);
  text-decoration-thickness: 2px;
  text-underline-offset: 6px;
  text-decoration-skip-ink: none;
}
.cta { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 28px; }
.btn {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  gap: 8px;
  min-height: 46px;
  padding: 12px 20px;
  border: 1px solid var(--line-strong);
  border-radius: var(--r-ctl);
  background: var(--bg-panel);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 15.5px;
  font-weight: var(--weight-bold);
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  transition: background-color var(--ease), border-color var(--ease), color var(--ease);
}
.btn svg { width: 17px; height: 17px; }
.btn-primary { background: var(--accent); color: var(--on-accent); border-color: var(--accent-dark); box-shadow: var(--shadow-btn); }
.btn-primary:hover, .btn-primary.is-hover { background: var(--accent-dark); color: var(--on-accent); }
.btn-ghost:hover, .btn-ghost.is-hover { border-color: var(--accent); color: var(--accent); }
.btn.is-focus { outline: 2px solid var(--accent); outline-offset: 4px; box-shadow: var(--focus-ring); }
.btn:disabled, .btn[aria-disabled="true"] { background: var(--bg-panel-2); color: var(--text-muted); border-color: var(--border); box-shadow: none; }
.card, .panel {
  min-width: 0;
  padding: var(--space-card);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  background: var(--bg-panel);
  color: var(--text);
  box-shadow: var(--shadow-card);
}
.panel { border-radius: var(--r-panel); box-shadow: var(--shadow-panel); }
.card h3 { margin: 0 0 12px; }
.card > :last-child { margin-bottom: 0; }
.topbar { height: var(--nav-h); border-bottom: 1px solid var(--border); background: var(--bg); color: var(--text); position: relative; z-index: var(--header-z); }
.header-wrap {
  height: 100%;
  width: 100%;
  max-width: min(100%, calc(var(--header-content) + var(--gutter) * 2));
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: stretch;
  gap: clamp(20px, 3vw, 36px);
}
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; color: var(--text); flex-shrink: 0; }
.brand:hover { color: var(--text); }
.brand-mark { width: 32px; height: 32px; display: block; flex-shrink: 0; }
.brand-name { font-family: var(--font-display); font-weight: var(--weight-heavy); font-size: 19px; letter-spacing: -.02em; }
.desktop-nav { margin-left: auto; min-width: 0; display: flex; }
.tabs {
  display: flex;
  align-items: center;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: clamp(16px, 2.1vw, 30px);
}
.tabs li { display: flex; height: 100%; }
.tabs a {
  position: relative;
  display: flex;
  align-items: center;
  padding-inline: 2px;
  font-size: 15px;
  font-weight: var(--weight-medium);
  color: var(--text-muted);
  text-decoration: none;
  white-space: nowrap;
}
.tabs a:hover { color: var(--text); }
.tabs a[aria-current="page"] { color: var(--text); font-weight: var(--weight-bold); }
.tabs a[aria-current="page"]::after {
  content: "";
  position: absolute;
  inset-inline: 0;
  bottom: -1px;
  height: 3px;
  border-radius: var(--r-tab);
  background: var(--accent);
}
.header-tools { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.language-picker { position: relative; }
.lang {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 34px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--r-ctl);
  background: var(--bg-panel);
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  line-height: 1;
  white-space: nowrap;
}
.lang svg { width: 14px; height: 14px; color: var(--text-muted); }
.caret { color: var(--text-muted); font-size: 11px; }
.lang-short { display: none; }
.language-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: 184px;
  padding: 6px;
  margin: 0;
  list-style: none;
  background: var(--bg-panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  box-shadow: var(--shadow-panel);
}
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 8px 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-2); color: var(--accent-dark); }
.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-ctl);
  background: var(--bg-panel);
  color: var(--text);
}
.menu-toggle svg { width: 22px; height: 22px; }
.mobile-drawer { display: none; }
.nav-veil { position: fixed; inset: var(--nav-h) 0 0; z-index: var(--veil-z); background: var(--veil); color: var(--text); border: 0; }
.static-language > summary { list-style: none; }
.static-language > summary::-webkit-details-marker { display: none; }
.static-mobile { display: none; }
.site-footer {
  border-top: 1px solid var(--border);
  padding-top: 56px;
  padding-bottom: 24px;
  background: var(--bg);
  color: var(--text);
}
.footer-grid { display: grid; grid-template-columns: 1.25fr .8fr 1.5fr .8fr; gap: 40px; }
.footer-intro { margin-top: 18px; max-width: 24em; color: var(--text-muted); font-size: var(--text-sm); }
.footer-heading { margin: 0 0 16px; font-size: var(--text-base); font-weight: var(--weight-bold); }
.footer-links { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.footer-links a { color: var(--text-muted); text-decoration: none; overflow-wrap: break-word; }
.footer-links a:hover { color: var(--accent); text-decoration: underline; }
.footer-bottom { border-top: 1px solid var(--border); margin-top: 36px; padding-top: 20px; color: var(--text-muted); font-size: var(--text-sm); }
.reveal { opacity: 1; }
.reveal-ready .reveal:not(.shown) { opacity: 0; transform: translateY(16px); }
.reveal-ready .reveal { transition: opacity var(--reveal-time) ease, transform var(--reveal-time) ease; }
.reveal-ready .reveal.shown { opacity: 1; transform: none; }
.decorated, .hero { overflow-x: clip; }
@media (max-width: 1100px) {
  .desktop-nav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .mobile-drawer:not([hidden]) {
    display: block;
    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(--bg-panel);
    color: var(--text);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-panel);
  }
  .mobile-drawer ul { list-style: none; padding: 0; margin: 0; }
  .mobile-drawer a { width: 100%; min-height: 46px; display: flex; align-items: center; padding: 11px 12px; color: var(--text); text-decoration: none; border-bottom: 1px solid var(--border); }
  .mobile-drawer a[aria-current] { color: var(--accent-dark); background: var(--accent-soft); }
  .drawer-caption { color: var(--text-muted); font-size: var(--text-sm); margin: 24px 12px 8px; }
  .static-mobile { display: block; }
  .static-mobile > summary { display: flex; }
  .static-mobile nav { position: absolute; top: var(--nav-h); inset-inline: 0; padding: 16px var(--gutter); background: var(--bg-panel); color: var(--text); border-bottom: 1px solid var(--border); max-height: calc(100dvh - var(--nav-h)); overflow: auto; }
  .static-mobile nav a { display: block; padding: 12px; min-height: 46px; color: var(--text); text-decoration: none; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .split { gap: 32px; }
}
@media (max-width: 768px) {
  :root { --title-xl: clamp(24px, 7vw, 30px); --title-lg: 28px; --section-space: 56px; }
  .grid-3 { grid-template-columns: 1fr; }
  .split { grid-template-columns: 1fr; gap: 24px; }
  .sticky-heading { position: static; }
}
@media (max-width: 640px) {
  :root { --gutter: 20px; --space-card: 20px; }
  .grid-2, .footer-grid { grid-template-columns: 1fr; }
  .header-wrap { gap: 12px; }
  .brand-name { font-size: 17px; }
  .header-tools { gap: 6px; margin-left: auto; }
  .lang { padding-inline: 10px; min-height: 40px; }
  .lang-full { display: none; }
  .lang-short { display: inline; }
  .tilt, [data-tilt] { transform: none !important; }
  .footer-grid { gap: 28px; }
  .cta { gap: 10px; }
  pre { padding: 16px; }
}
@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; }
}