:root {
  --bg: #FEFEFE;
  --bg-soft: #FBFBFC;
  --bg-panel: #F5F6F8;
  --bg-panel-2: #ECEEF2;
  --surface: #FFFFFF;
  --border: #E3E5EA;
  --border-strong: #D2D5DC;
  --grid-line: #D8DBE1;
  --skeleton: #E4E6EB;
  --accent: #155EEF;
  --accent-dark: #0B45C2;
  --accent-soft: rgba(21, 94, 239, 0.09);
  --on-accent: #FFFFFF;
  --text: #0C0D10;
  --text-muted: #5B606B;
  --text-faint: #8A8F99;
  --success: #12A150;
  --success-soft: rgba(18, 161, 80, 0.18);
  --warn: #C98A06;
  --error: #D93B2B;
  --ink: #08090B;
  --ink-2: #121418;
  --ink-3: #1A1D22;
  --ink-line: #1E2026;
  --skeleton-ink: #2A2E36;
  --on-ink: #F2F3F5;
  --on-ink-muted: #8B909A;
  --mask-solid: #000000;
  --mask-clear: transparent;
  --veil: rgba(12, 13, 16, 0.38);

  --font-display: "Inter", "Noto Sans SC", "PingFang SC", "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", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --weight-body: 400;
  --weight-medium: 500;
  --weight-semibold: 600;
  --weight-bold: 700;
  --weight-heavy: 800;
  --weight-display: 900;
  --text-xs: 12px;
  --text-sm: 14px;
  --text-base: 16px;
  --text-lg: 20px;
  --title-size: clamp(34px, 2.4vw + 14px, 48px);
  --section-size: clamp(24px, 2.6vw, 36px);
  --tracking-title: -0.02em;
  --tracking-small: -0.01em;

  --r-ctl: 6px;
  --r-card: 10px;
  --r-pop: 12px;
  --r-win: 8px;
  --r-phone: 22px;
  --r-pill: 999px;
  --r-tiny: 3px;
  --r-circle: 50%;

  --shadow-hairline: 0 1px 2px rgba(12, 13, 16, 0.04);
  --shadow-btn: 0 1px 2px rgba(11, 69, 194, 0.28), inset 0 1px 0 rgba(255, 255, 255, 0.14);
  --shadow-win: 0 1px 2px rgba(12, 13, 16, 0.05), 0 12px 28px -18px rgba(12, 13, 16, 0.28);
  --shadow-card-hover: 0 1px 2px rgba(12, 13, 16, 0.04), 0 22px 44px -26px rgba(12, 13, 16, 0.26);
  --shadow-pop: 0 0 0 1px rgba(12, 13, 16, 0.05), 0 2px 4px rgba(12, 13, 16, 0.04), 0 14px 28px -12px rgba(12, 13, 16, 0.20), 0 38px 70px -30px rgba(12, 13, 16, 0.26);
  --shadow-fab: 0 6px 14px -6px rgba(11, 69, 194, 0.55);
  --nav-h: 64px;
  --peek: 40px;
  --container: 1232px;
  --reading: 820px;
  --gutter: 24px;
  --section-space: 88px;
  --ease: cubic-bezier(0.2, 0.7, 0.2, 1);
  --transition: 0.2s;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 24px; }
html, body { margin: 0; padding: 0; }
html.nav-open { overflow: hidden; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}
[hidden] { display: none !important; }
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
button, input, select, textarea { max-width: 100%; }
img, video, svg { max-width: 100%; }
img, video { height: auto; }
svg { vertical-align: middle; }
button svg, a svg, .dot, .badge-dot { flex-shrink: 0; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }
a:focus-visible, button:focus-visible { border-radius: var(--r-ctl); }
::selection { background: var(--accent); color: var(--on-accent); }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  color: var(--text);
  text-wrap: balance;
  line-height: 1.2;
  letter-spacing: var(--tracking-title);
}
h1 { font-size: var(--title-size); font-weight: var(--weight-display); line-height: 1.12; }
h2 { font-size: var(--section-size); font-weight: var(--weight-heavy); }
h3 { font-size: var(--text-lg); font-weight: var(--weight-bold); }
p { margin: 0 0 1.25em; }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; font-size: 0.88em; }
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 20px;
  background: var(--bg-panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-win);
  line-height: 1.75;
  tab-size: 2;
}
pre code { overflow-wrap: normal; word-break: normal; white-space: pre; }
hr { border: 0; border-top: 1px solid var(--border); margin: 32px 0; }
.wrap {
  width: 100%;
  max-width: calc(var(--container) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.reading { max-width: calc(var(--reading) + var(--gutter) * 2); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-head { max-width: 720px; margin-bottom: 32px; }
.section-head h2 { margin: 0 0 16px; }
.muted { color: var(--text-muted); }
.mono { font-family: var(--font-mono); }
.keep { white-space: nowrap; }
.text-link { color: var(--accent-dark); text-decoration: underline; text-underline-offset: 4px; }
.text-link:hover { color: var(--accent); }
.grid { display: grid; gap: 20px; grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid > *, .footer-grid > *, .feature-layout > *, .prose > * { min-width: 0; }
.stack > * + * { margin-top: 20px; }
.prose { line-height: 1.85; min-width: 0; }
.prose h2 { margin-top: 2em; margin-bottom: 0.75em; }
.prose h3 { margin-top: 1.5em; }
.prose li + li { margin-top: 8px; }
.prose a { color: var(--accent-dark); text-decoration: underline; text-underline-offset: 3px; }
.prose :not(pre) > code { background: var(--bg-panel); color: var(--text); padding: 2px 5px; border-radius: var(--r-tiny); }
.decorated, [data-hero-visual] { overflow-x: clip; }
.card, .panel {
  min-width: 0;
  padding: 24px;
  background: var(--bg-panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
}
.card h3, .panel h3 { margin-top: 0; }
.card p:last-child, .panel p:last-child { margin-bottom: 0; }
.card-link { display: block; transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease); }
.card-link:hover { transform: translateY(-4px); box-shadow: var(--shadow-card-hover); }
.actions { display: flex; align-items: center; justify-content: center; gap: 12px; margin-top: 26px; flex-wrap: wrap; }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 10px 20px;
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: var(--weight-semibold);
  letter-spacing: -0.005em;
  border: 1px solid var(--mask-clear);
  border-radius: var(--r-ctl);
  transition: background-color var(--transition) var(--ease), border-color var(--transition) var(--ease), color var(--transition) var(--ease);
}
.btn svg { width: 16px; height: 16px; }
.btn-primary { color: var(--on-accent); background: var(--accent); box-shadow: var(--shadow-btn); }
.btn-primary:hover, .btn-primary.is-hover { background: var(--accent-dark); color: var(--on-accent); }
.btn-primary:active, .btn-primary.is-active { background: var(--accent-dark); color: var(--on-accent); box-shadow: none; }
.btn-secondary { color: var(--text); background: var(--surface); border-color: var(--border); box-shadow: var(--shadow-hairline); }
.btn-secondary:hover, .btn-secondary.is-hover { color: var(--text); border-color: var(--border-strong); background: var(--bg-panel); }
.btn-secondary:active { background: var(--bg-panel-2); color: var(--text); }
.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; }

.topbar { position: relative; z-index: 30; min-height: var(--nav-h); background: var(--bg); color: var(--text); border-bottom: 1px solid var(--border); }
.topbar-inner {
  max-width: min(100%, calc(1280px + var(--gutter) * 2));
  min-height: calc(var(--nav-h) - 1px);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; font-family: var(--font-display); font-size: 16px; font-weight: var(--weight-heavy); letter-spacing: var(--tracking-small); flex-shrink: 0; }
.brand-mark { width: 30px; height: 30px; flex-shrink: 0; }
.nav { display: flex; align-items: center; margin-left: auto; min-width: 0; }
.nav-list { display: flex; align-items: center; list-style: none; margin: 0; padding: 0; gap: 30px; }
.nav-link { display: block; padding: 8px 0; font-size: 14.5px; font-weight: var(--weight-medium); color: var(--text-muted); white-space: nowrap; transition: color var(--transition) var(--ease); }
.nav-link:hover { color: var(--text); }
.nav-link[aria-current="page"] { color: var(--text); font-weight: var(--weight-bold); }
.header-tools { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.nav-sep { width: 1px; height: 18px; background: var(--border); color: var(--text); margin-right: 10px; }
.language-control { position: relative; }
.lang { display: inline-flex; align-items: center; justify-content: center; gap: 6px; min-height: 34px; padding: 6px 12px; font-size: 14px; font-weight: var(--weight-medium); color: var(--text); background: var(--surface); border: 1px solid var(--border); border-radius: var(--r-ctl); }
.lang:hover { background: var(--bg-panel); color: var(--text); border-color: var(--border-strong); }
.lang-caret { font-size: 10px; }
.lang-short { display: none; }
.language-menu { position: absolute; z-index: 40; top: calc(100% + 10px); right: 0; width: 180px; margin: 0; padding: 6px; list-style: none; background: var(--surface); color: var(--text); border: 1px solid var(--border); border-radius: var(--r-win); box-shadow: var(--shadow-pop); }
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 10px 12px; border-radius: var(--r-ctl); }
.language-menu a:hover, .language-menu a[aria-current="true"] { background: var(--bg-panel); color: var(--text); }
.menu-toggle { display: none; min-width: 44px; min-height: 44px; align-items: center; justify-content: center; border: 1px solid var(--border); border-radius: var(--r-ctl); background: var(--surface); color: var(--text); }
.menu-toggle svg { width: 20px; height: 20px; }
.mobile-drawer { display: none; }
.menu-veil { position: fixed; z-index: 20; inset: var(--nav-h) 0 0; background: var(--veil); color: var(--on-ink); border: 0; width: 100%; }
.site-footer { border-top: 1px solid var(--border); background: var(--bg-panel); color: var(--text); padding-top: 56px; padding-bottom: 28px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 0.8fr 1.2fr 0.8fr; gap: 40px; }
.footer-about p { max-width: 320px; margin-top: 16px; font-size: var(--text-sm); color: var(--text-muted); line-height: 1.8; }
.footer-heading { margin: 0 0 16px; font-size: var(--text-sm); font-weight: var(--weight-bold); }
.footer-list { list-style: none; padding: 0; margin: 0; }
.footer-list li + li { margin-top: 8px; }
.footer-list a { display: inline-block; padding-block: 3px; font-size: var(--text-sm); color: var(--text-muted); overflow-wrap: anywhere; }
.footer-list a:hover { color: var(--accent-dark); text-decoration: underline; }
.footer-bottom { display: flex; justify-content: space-between; align-items: center; gap: 20px; flex-wrap: wrap; margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--border); color: var(--text-muted); font-size: var(--text-xs); }
.footer-bottom p { margin: 0; }
.reveal { opacity: 1; transform: none; }
html.reveal-ready .reveal:not(.shown) { opacity: 0; transform: translateY(14px); }
html.reveal-ready .reveal { transition: opacity 0.65s var(--ease), transform 0.65s var(--ease); }
.reveal.shown { opacity: 1; transform: none; }

@media (max-width: 1100px) {
  .nav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .nav-sep { display: none; }
  .mobile-drawer {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: block;
    padding: 16px var(--gutter) 24px;
    max-height: calc(100dvh - var(--nav-h));
    overflow-y: auto;
    overscroll-behavior: contain;
    background: var(--surface);
    color: var(--text);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-win);
  }
  .mobile-drawer ul { list-style: none; margin: 0; padding: 0; }
  .mobile-drawer a { display: flex; align-items: center; width: 100%; min-height: 44px; padding: 12px 10px; font-size: var(--text-sm); border-radius: var(--r-ctl); }
  .mobile-drawer a:hover, .mobile-drawer a[aria-current] { background: var(--bg-panel); color: var(--text); font-weight: var(--weight-bold); }
  .drawer-languages { margin-top: 16px !important; padding-top: 16px !important; border-top: 1px solid var(--border); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 768px) {
  h1 { font-size: 28px; }
  h1 .keep, h2 .keep { white-space: normal; }
  .grid { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 640px) {
  :root { --gutter: 18px; --section-space: 56px; }
  .topbar-inner { gap: 8px; }
  .brand { font-size: 14px; gap: 7px; }
  .brand-mark { width: 28px; height: 28px; }
  .header-tools { gap: 6px; margin-left: auto; }
  .lang-full { display: none; }
  .lang-short { display: inline; }
  .lang { min-height: 44px; padding-inline: 10px; }
  .tilt, [data-tilt] { transform: none !important; }
  .footer-grid { gap: 28px; }
  .footer-about { grid-column: 1 / -1; }
  .card, .panel { padding: 20px; }
}
@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; }
  .card-link:hover { transform: none; }
}