:root {
  --bg: #276AA5;
  --bg-panel: #1C4B7A;
  --bg-panel-2: #2F70AC;
  --arc-bright: #3A82C2;
  --border: #709BC2;
  --accent: #42C2EA;
  --accent-dark: #A4E9FF;
  --on-accent: #13283F;
  --sun: #FFC24B;
  --blossom: #F6A3C4;
  --text: #F4F8FC;
  --text-muted: #D4E5F5;
  --success: #3FCB8E;
  --warn: #FFC24B;
  --error: #F26B6B;
  --surface: #276AA5;
  --surface-soft: #205B90;
  --ink: #F4F8FC;
  --ink-muted: #D4E5F5;
  --line-soft: #709BC2;
  --control-off: #709BC2;
  --white-rgb: 255 255 255;
  --shadow-rgb: 9 30 56;
  --accent-rgb: 66 194 234;
  --clear: transparent;
  --font-display: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', system-ui, sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  --r-input: 8px;
  --r-btn: 12px;
  --r-card: 20px;
  --r-card-lg: 24px;
  --r-plate: 28px;
  --r-section: 32px;
  --r-phone: 34px;
  --r-screen: 27px;
  --r-pill: 999px;
  --r-circle: 50%;
  --gutter: 32px;
  --content-width: 1160px;
  --reading-width: 800px;
  --header-width: 1280px;
  --header-height: 72px;
  --space-section: 104px;
  --motion-fast: .2s;
  --motion-reveal: .6s;
  --shadow-btn: inset 0 1px 0 rgb(var(--white-rgb) / .45), 0 4px 10px rgb(var(--shadow-rgb) / .20), 0 14px 30px rgb(var(--shadow-rgb) / .22);
  --shadow-window: 0 1px 2px rgb(var(--shadow-rgb) / .10), 0 10px 24px rgb(var(--shadow-rgb) / .16), 0 30px 60px rgb(var(--shadow-rgb) / .22), 0 64px 120px rgb(var(--shadow-rgb) / .18);
  --shadow-phone: 0 2px 4px rgb(var(--shadow-rgb) / .18), 0 18px 34px rgb(var(--shadow-rgb) / .28), 0 44px 84px rgb(var(--shadow-rgb) / .34);
  --shadow-fab: 0 3px 6px rgb(var(--shadow-rgb) / .22), 0 10px 20px rgb(var(--shadow-rgb) / .22);
  --shadow-card: 0 2px 4px rgb(var(--shadow-rgb) / .04), 0 16px 40px rgb(var(--shadow-rgb) / .08);
  --shadow-nav: 0 2px 6px rgb(var(--shadow-rgb) / .18);
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 32px; }
html, body { margin: 0; }
html.nav-open { overflow: hidden; }
body {
  background: var(--surface);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
[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 { cursor: pointer; }
a { color: var(--accent-dark); text-underline-offset: .2em; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
::selection { background: var(--accent); color: var(--on-accent); }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--ink);
  line-height: 1.25;
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 { font-size: clamp(34px, 3.4vw, 48px); font-weight: 800; letter-spacing: -.02em; }
h2 { font-size: clamp(24px, 2.6vw, 32px); font-weight: 800; letter-spacing: -.02em; }
h3 { font-size: 22px; font-weight: 700; }
p, ul, ol, dl { margin-top: 0; }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; font-size: .88em; }
:not(pre) > code {
  background: var(--surface-soft);
  color: var(--ink);
  padding: .12em .35em;
  border-radius: var(--r-input);
}
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 24px;
  border: 1px solid var(--line-soft);
  border-radius: var(--r-card);
  background: var(--surface-soft);
  color: var(--ink);
  font-size: 13px;
  line-height: 1.8;
  tab-size: 2;
}
pre code { white-space: pre; overflow-wrap: normal; word-break: normal; font-size: inherit; }
.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-heading { max-width: 720px; margin-bottom: 40px; }
.section-heading p, .muted { color: var(--ink-muted); }
.keep { white-space: nowrap; }
.kw { color: var(--accent-dark); }
.grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 24px; }
.grid > *, .flex > *, .prose, .prose > *, main { min-width: 0; }
.flex { display: flex; flex-wrap: wrap; align-items: center; gap: 14px; }
.card, .panel {
  min-width: 0;
  padding: 28px;
  border-radius: var(--r-card-lg);
  border: 1px solid var(--line-soft);
  background: var(--surface);
  color: var(--ink);
  box-shadow: var(--shadow-card);
}
.panel {
  border-radius: var(--r-plate);
  background: var(--surface-soft);
  color: var(--ink);
  border-color: var(--surface-soft);
  box-shadow: none;
}
.card h3 { margin-top: 0; }
.card p:last-child, .panel p:last-child { margin-bottom: 0; }
.prose { overflow-wrap: break-word; }
.prose h2 { margin-top: 64px; margin-bottom: 24px; scroll-margin-top: 32px; }
.prose h3 { margin-top: 36px; }
.prose p { margin-bottom: 24px; }
.prose li { margin-bottom: 10px; }
.prose img { margin-block: 24px; }
.btn {
  display: inline-flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
  min-height: 50px;
  padding: 10px 24px;
  border: 1px solid var(--clear);
  border-radius: var(--r-btn);
  font-size: 16px;
  font-weight: 700;
  line-height: 1.5;
  text-align: center;
  text-decoration: none;
  transition: transform var(--motion-fast) ease, background-color var(--motion-fast) ease;
}
.btn svg { width: 18px; height: 18px; }
.btn-primary { background: var(--accent); color: var(--on-accent); box-shadow: var(--shadow-btn); }
.badge-top, .dl-fab { --ink: var(--on-accent); }
.btn-primary:hover, .btn-primary.is-hover { transform: translateY(-1px); }
.btn-primary:active, .btn-primary.is-active { transform: translateY(1px); box-shadow: var(--shadow-nav); }
.btn-ghost {
  background: rgb(var(--white-rgb) / .04);
  color: var(--text);
  border-color: rgb(var(--white-rgb) / .42);
}
.btn-ghost:hover, .btn-ghost.is-hover { background: rgb(var(--white-rgb) / .10); color: var(--text); }
.btn-secondary { background: var(--surface); color: var(--ink); border-color: var(--line-soft); }
.btn-secondary:hover { background: var(--surface-soft); color: var(--ink); }
.btn:disabled, .btn[aria-disabled="true"] {
  background: var(--surface-soft);
  color: var(--ink-muted);
  border-color: var(--line-soft);
  box-shadow: none;
  cursor: not-allowed;
  transform: none;
}
.btn.is-focus { outline: 2px solid var(--accent-dark); outline-offset: 3px; }
.deep-section {
  position: relative;
  overflow-x: clip;
  background: var(--bg);
  color: var(--text);
}
.deep-section h2, .deep-section h3 { color: var(--text); }
.deep-section p { color: var(--text-muted); }
.deep-section .kw { color: var(--accent); }
.topbar, #site-header {
  position: relative;
  z-index: 30;
  min-height: var(--header-height);
  background: var(--bg);
  color: var(--text);
}
.hero .topbar, .hero #site-header { background: var(--clear); color: var(--text); }
.topbar-inner {
  position: relative;
  width: 100%;
  max-width: min(100%, calc(var(--header-width) + var(--gutter) * 2));
  min-height: var(--header-height);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 24px;
}
.brand {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
  gap: 11px;
  color: var(--text);
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -.01em;
  line-height: 1.4;
  text-decoration: none;
}
.brand img { width: 34px; height: 34px; flex-shrink: 0; }
.nav { margin-left: auto; min-width: 0; }
.nav ul {
  display: flex;
  align-items: center;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 2px;
  border: 1px solid rgb(var(--white-rgb) / .12);
  border-radius: var(--r-pill);
  background: rgb(var(--white-rgb) / .07);
  color: var(--text);
}
.nav li:first-child { margin-left: 5px; }
.nav li:last-child { margin-right: 5px; }
.nav a {
  display: block;
  margin-block: 5px;
  padding: 8px 16px;
  border-radius: var(--r-pill);
  color: var(--text-muted);
  font-size: 14.5px;
  font-weight: 600;
  line-height: 1.5;
  white-space: nowrap;
  text-decoration: none;
}
.nav a:hover { color: var(--text); background: rgb(var(--white-rgb) / .07); }
.nav a[aria-current="page"] {
  color: var(--ink);
  background: var(--surface);
  box-shadow: var(--shadow-nav);
}
.header-tools { display: flex; align-items: center; gap: 8px; flex-shrink: 0; }
.language-picker { position: relative; }
.lang {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 38px;
  padding: 8px 14px;
  border: 1px solid rgb(var(--white-rgb) / .24);
  border-radius: var(--r-pill);
  background: var(--clear);
  color: var(--text);
  font-size: 14px;
  font-weight: 600;
  line-height: 1.4;
  white-space: nowrap;
}
.lang svg { width: 16px; height: 16px; }
.lang:hover { background: rgb(var(--white-rgb) / .07); color: var(--text); }
.lang-short { display: none; }
.language-menu {
  position: absolute;
  z-index: 5;
  top: calc(100% + 12px);
  right: 0;
  min-width: 180px;
  margin: 0;
  padding: 8px;
  list-style: none;
  border: 1px solid var(--line-soft);
  border-radius: var(--r-card);
  background: var(--surface);
  color: var(--ink);
  box-shadow: var(--shadow-card);
}
.language-menu a, .mobile-drawer a {
  display: flex;
  align-items: center;
  width: 100%;
  min-height: 44px;
  padding: 10px 16px;
  border-radius: var(--r-btn);
  text-decoration: none;
}
.language-menu a { color: var(--ink); }
.language-menu a:hover, .language-menu a[aria-current="true"] { background: var(--surface-soft); color: var(--ink); }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  border: 1px solid rgb(var(--white-rgb) / .24);
  border-radius: var(--r-btn);
  background: var(--clear);
  color: var(--text);
}
.menu-toggle svg { width: 22px; height: 22px; }
.mobile-drawer, .nav-veil { display: none; }
.site-footer {
  position: relative;
  overflow-x: clip;
  isolation: isolate;
  padding-top: 88px;
  padding-bottom: 28px;
  border-radius: var(--r-section) var(--r-section) 0 0;
  background: var(--bg);
  color: var(--text);
}
.site-footer::before {
  content: "";
  position: absolute;
  z-index: -1;
  width: 900px;
  height: 900px;
  right: -240px;
  bottom: -740px;
  border: 100px solid var(--bg-panel-2);
  border-radius: var(--r-circle);
  background: var(--bg-panel);
  color: var(--text);
}
.footer-grid { display: grid; grid-template-columns: 1.2fr .8fr 1.2fr .7fr; gap: 40px; }
.footer-grid > * { min-width: 0; }
.footer-brand p { max-width: 310px; margin-top: 20px; color: var(--text-muted); font-size: 14px; }
.footer-title { margin: 0 0 18px; color: var(--text); font-size: 15px; font-weight: 700; }
.footer-links { display: grid; gap: 10px; list-style: none; padding: 0; margin: 0; }
.footer-links a { color: var(--text-muted); text-decoration: none; font-size: 14px; }
.footer-links a:hover { color: var(--text); text-decoration: underline; }
.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 16px;
  margin-top: 64px;
  padding-top: 24px;
  border-top: 1px solid rgb(var(--white-rgb) / .18);
  color: var(--text-muted);
  font-size: 13px;
}
.footer-legal { display: flex; flex-wrap: wrap; gap: 20px; }
.footer-legal a { color: var(--text-muted); }
.reveal { opacity: 1; transform: none; }
.reveal-pending { opacity: 0; transform: translateY(18px); transition: opacity var(--motion-reveal) ease, transform var(--motion-reveal) ease; }
.reveal.shown { opacity: 1; transform: none; }
@media (max-width: 1279px) {
  .desktop-nav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .mobile-drawer:not([hidden]) {
    display: block;
    position: absolute;
    z-index: 4;
    top: 100%;
    left: 0;
    right: 0;
    padding: 16px var(--gutter) 24px;
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
    overscroll-behavior: contain;
    border-top: 1px solid var(--border);
    background: var(--bg-panel);
    color: var(--text);
  }
  .mobile-drawer ul { list-style: none; padding: 0; margin: 0; }
  .mobile-drawer a { color: var(--text); }
  .mobile-drawer a:hover { background: var(--bg); color: var(--text); }
  .mobile-drawer a[aria-current="page"] { background: var(--surface); color: var(--ink); }
  .drawer-label { margin: 20px 16px 8px; font-size: 13px; color: var(--text-muted); }
  .nav-veil:not([hidden]) {
    display: block;
    position: fixed;
    z-index: -1;
    inset: var(--header-height) 0 0;
    border: 0;
    background: rgb(var(--shadow-rgb) / .55);
    color: var(--text);
  }
}
@media (max-width: 768px) {
  :root { --gutter: 20px; --space-section: 72px; }
  h1 { font-size: clamp(24px, 4.5vw, 30px); }
  .grid { grid-template-columns: minmax(0, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 32px; }
}
@media (max-width: 640px) {
  :root { --gutter: 16px; }
  .tilt, .win-wrap { transform: none !important; }
  .topbar-inner { gap: 8px; }
  .brand { font-size: 16px; gap: 8px; }
  .brand img { width: 30px; height: 30px; }
  .lang { padding-inline: 10px; min-height: 44px; }
  .lang-full { display: none; }
  .lang-short { display: inline; }
  .card, .panel { padding: 22px; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-bottom { margin-top: 40px; }
  pre { padding: 18px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
  .reveal-pending { opacity: 1; transform: none; }
}