:root {
  --bg: #FFFFFF;
  --paper: #FFFFFF;
  --panel-lime: #EFFAE0;
  --panel-lav: #F1ECFD;
  --line: #E6E6E8;
  --line-strong: #C9C9CE;
  --surface: #F5F5F7;
  --accent: #F2385A;
  --accent-dark: #C21F40;
  --ink: #121212;
  --muted: #6B6B72;
  --muted-ink: #9C9CA5;
  --line-ink: #2C2C31;
  --success: #1FA67A;
  --warn: #D99A00;
  --error: #D92D20;
  --lime: #D8F36A;
  --cobalt: #2F5BFF;
  --mint: #3ED6A4;
  --clear: transparent;
  --white-wash: color-mix(in srgb, var(--paper) 55%, transparent);
  --ink-wash: color-mix(in srgb, var(--ink) 14%, transparent);
  --switch-off: color-mix(in srgb, var(--ink) 18%, transparent);
  --switch-dark-off: color-mix(in srgb, var(--paper) 22%, transparent);

  --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", "Apple SD Gothic Neo", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --weight-regular: 400;
  --weight-medium: 500;
  --text-xs: 12px;
  --text-sm: 14px;
  --text-base: 16px;
  --text-lede: 17px;
  --h1-size: clamp(34px, 3.3vw, 48px);
  --h2-size: clamp(26px, 3vw, 36px);
  --h3-size: 22px;

  --r-xl: 32px;
  --r-board: 28px;
  --r-card: 22px;
  --r-md: 14px;
  --r-sm: 10px;
  --r-focus: 6px;
  --r-highlight: 8px;
  --r-mint: 24px;
  --r-pill: 999px;
  --r-round: 50%;
  --gutter: 64px;
  --nav-h: 68px;
  --peek: 40px;
  --wrap-width: 1440px;
  --reading-width: 880px;
  --header-content: 1280px;
  --section-space: 112px;
  --motion-fast: .2s;
  --motion-reveal: .55s;
  --ease: ease;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
html.nav-open { overflow: hidden; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
[hidden] { display: none !important; }
img, svg { vertical-align: middle; }
img { max-width: 100%; height: auto; }
a { color: inherit; text-underline-offset: .22em; }
button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
button:disabled { cursor: not-allowed; }
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: var(--r-focus);
}
::selection { background: var(--panel-lav); color: var(--ink); }
h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: var(--weight-regular);
  line-height: 1.2;
  text-wrap: balance;
}
h1 { font-size: var(--h1-size); letter-spacing: -.02em; }
h2 { font-size: var(--h2-size); letter-spacing: -.015em; }
h3 { font-size: var(--h3-size); letter-spacing: -.01em; }
p { margin-top: 0; }
strong { font-weight: var(--weight-medium); }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; }
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 24px;
  background: var(--surface);
  color: var(--ink);
  border-radius: var(--r-md);
  font-size: var(--text-sm);
  line-height: 1.8;
  -webkit-overflow-scrolling: touch;
}
pre code { overflow-wrap: normal; word-break: normal; white-space: pre; }
hr { border: 0; border-top: 1px solid var(--line); margin-block: 40px; }
section, article, aside, main, nav, .grid > *, .two-col > * { min-width: 0; }
[id] { scroll-margin-top: 28px; }
.wrap {
  width: 100%;
  max-width: var(--wrap-width);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.reading { max-width: calc(var(--reading-width) + var(--gutter) * 2); margin-inline: auto; padding-inline: var(--gutter); }
.section { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.section-title { margin: 0 0 32px; }
.two-col { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 56px; }
.stack > * + * { margin-top: 24px; }
.muted { color: var(--muted); }
.mono { font-family: var(--font-mono); }
.keep { white-space: nowrap; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}
.text-link {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 5px;
}
.text-link:hover { text-decoration-thickness: 2px; }
.icon { width: 20px; height: 20px; flex-shrink: 0; fill: none; stroke: currentColor; stroke-width: 1.6; }
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 52px;
  padding: 12px 24px;
  border: 1px solid var(--clear);
  border-radius: var(--r-md);
  font-size: var(--text-base);
  font-weight: var(--weight-medium);
  line-height: 1.4;
  text-align: center;
  text-decoration: none;
  max-width: 100%;
  transition: background-color var(--motion-fast) var(--ease), border-color var(--motion-fast) var(--ease), color var(--motion-fast) var(--ease);
}
.btn svg { width: 18px; height: 18px; flex-shrink: 0; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.btn-primary { background: var(--accent); color: var(--paper); }
.btn-primary:hover, .btn-primary.is-hover { background: var(--accent-dark); color: var(--paper); }
.btn-primary:active { background: var(--accent-dark); color: var(--paper); }
.btn-ghost { background: var(--bg); color: var(--ink); border-color: var(--line); font-weight: var(--weight-regular); }
.btn-ghost:hover, .btn-ghost.is-hover { border-color: var(--ink); }
.btn:disabled, .btn[aria-disabled="true"] { background: var(--surface); color: var(--muted); border-color: var(--line); }
.btn[aria-disabled="true"] { pointer-events: none; }
.btn.is-focus { outline: 2px solid var(--accent); outline-offset: 3px; }
.cta-row { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 40px; }

.topbar {
  height: var(--nav-h);
  border-bottom: 1px solid var(--line);
  background: var(--bg);
  color: var(--ink);
  position: relative;
  z-index: 30;
}
.header-shell {
  width: 100%;
  max-width: min(100%, calc(var(--header-content) + var(--gutter) * 2));
  padding-inline: var(--gutter);
  margin-inline: auto;
}
.topbar-inner { height: 100%; display: flex; align-items: center; gap: 36px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none; color: var(--ink); flex-shrink: 0; }
.brand-mark { width: 30px; height: 30px; display: block; flex-shrink: 0; }
.brand-name { font-size: var(--text-base); font-weight: var(--weight-medium); letter-spacing: -.01em; }
.mainnav { margin-left: auto; min-width: 0; }
.mainnav ul { display: flex; align-items: center; list-style: none; margin: 0; padding: 0; }
.mainnav li { display: flex; align-items: center; flex-shrink: 0; }
.mainnav li + li::before { content: "/"; color: var(--line-strong); margin: 0 14px; font-size: 15px; }
.mainnav a {
  font-size: 15px;
  text-decoration: none;
  color: var(--ink);
  padding: 4px 0;
  white-space: nowrap;
  background-image: linear-gradient(var(--accent), var(--accent));
  background-repeat: no-repeat;
  background-position: 0 100%;
  background-size: 0 2px;
  transition: background-size var(--motion-fast) var(--ease);
}
.mainnav a:hover, .mainnav a[aria-current="page"] { background-size: 100% 2px; }
.header-tools { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.language-picker { position: relative; }
.lang {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  flex-shrink: 0;
  background: var(--clear);
  color: var(--ink);
  border: 1px solid var(--line);
  border-radius: var(--r-pill);
  padding: 7px 14px;
  font-size: var(--text-sm);
  white-space: nowrap;
}
.lang:hover { border-color: var(--line-strong); }
.lang svg { width: 15px; height: 15px; fill: none; stroke: currentColor; stroke-width: 1.4; flex-shrink: 0; }
.lang-caret { color: var(--muted); font-size: var(--text-xs); }
.lang-short { display: none; }
.language-menu {
  position: absolute;
  top: calc(100% + 12px);
  right: 0;
  min-width: 190px;
  margin: 0;
  padding: 8px;
  list-style: none;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: var(--paper);
  color: var(--ink);
  z-index: 3;
}
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 8px 14px; text-decoration: none; border-radius: var(--r-sm); }
.language-menu a:hover { background: var(--surface); color: var(--ink); }
.language-menu a[aria-current] { text-decoration: underline; text-decoration-color: var(--accent); }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  background: var(--bg);
  color: var(--ink);
}
.menu-toggle svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.6; }
.mobile-drawer {
  position: absolute;
  top: 100%;
  inset-inline: 0;
  max-height: calc(100dvh - var(--nav-h));
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 20px var(--gutter) 32px;
  background: var(--paper);
  color: var(--ink);
  border-bottom: 1px solid var(--line);
  z-index: 2;
}
.mobile-drawer ul { list-style: none; margin: 0; padding: 0; }
.mobile-drawer a { display: flex; align-items: center; width: 100%; min-height: 48px; padding: 12px 4px; text-decoration: none; border-bottom: 1px solid var(--line); }
.mobile-drawer a[aria-current] { text-decoration: underline; text-decoration-color: var(--accent); text-underline-offset: 5px; }
.drawer-label { margin: 24px 0 8px; color: var(--muted); font-size: var(--text-sm); }
.nav-veil { position: fixed; inset: var(--nav-h) 0 0; border: 0; background: var(--ink); color: var(--paper); opacity: .16; z-index: 20; width: 100%; }

.site-footer { border-top: 1px solid var(--line); padding-top: 64px; padding-bottom: 32px; background: var(--bg); color: var(--ink); }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1.4fr 1fr; gap: 40px; }
.footer-grid > * { min-width: 0; }
.footer-brand p { margin: 18px 0 0; color: var(--muted); font-size: var(--text-sm); max-width: 29em; }
.footer-title { margin: 0 0 18px; font-size: var(--text-base); font-weight: var(--weight-regular); }
.footer-links { list-style: none; margin: 0; padding: 0; }
.footer-links li + li { margin-top: 10px; }
.footer-links a { font-size: var(--text-sm); text-decoration: none; overflow-wrap: anywhere; }
.footer-links a:hover { text-decoration: underline; text-decoration-color: var(--accent); }
.footer-links a[aria-current] { text-decoration: underline; text-decoration-color: var(--accent); }
.footer-bottom { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px 24px; border-top: 1px solid var(--line); margin-top: 48px; padding-top: 24px; color: var(--muted); font-size: 13px; }
.footer-legal { display: flex; flex-wrap: wrap; gap: 20px; }
.footer-legal a { color: var(--ink); text-decoration-color: var(--line-strong); }

.card { border: 1px solid var(--line); border-radius: var(--r-card); padding: 28px; background: var(--paper); color: var(--ink); }
.card h3 { margin: 0 0 16px; }
.card p:last-child { margin-bottom: 0; }
.panel {
  background: var(--panel-lime);
  color: var(--ink);
  border-radius: var(--r-xl);
  padding: 72px 64px 80px;
  display: grid;
  grid-template-columns: 300px minmax(0, 1fr);
  gap: 56px;
  align-items: start;
}
.panel > * { min-width: 0; }
.panel-lav { background: var(--panel-lav); color: var(--ink); }
.prose { min-width: 0; overflow-wrap: break-word; }
.prose h2 { margin: 64px 0 24px; }
.prose h3 { margin: 36px 0 18px; }
.prose p, .prose li { line-height: 1.85; }
.prose p { margin-bottom: 24px; }
.prose a { text-decoration-color: var(--accent); }
.prose :not(pre) > code { background: var(--surface); color: var(--ink); border-radius: var(--r-focus); padding: .1em .3em; font-size: .9em; }
.prose ul, .prose ol { padding-inline-start: 1.5em; }
.prose img { border-radius: var(--r-md); }
.decorated { position: relative; overflow-x: clip; }
.reveal { opacity: 1; }
.reveal-ready .reveal:not(.shown) { opacity: 0; transform: translateY(12px); }
.reveal-ready .reveal { transition: opacity var(--motion-reveal) var(--ease), transform var(--motion-reveal) var(--ease); }
.reveal.shown { opacity: 1; transform: none; }

@media (max-width: 1320px) {
  .topbar-inner { gap: 24px; }
  .mainnav li + li::before { margin-inline: 10px; }
}
@media (max-width: 1100px) {
  :root { --gutter: 40px; }
  .panel { grid-template-columns: minmax(0, 1fr); padding: 56px 40px; }
  #site-header .mainnav { display: none; }
  #site-header .header-tools { margin-left: auto; }
  #site-header .menu-toggle { display: inline-flex; }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (min-width: 1101px) {
  .mobile-drawer, .nav-veil { display: none !important; }
}
@media (max-width: 860px) {
  :root { --gutter: 20px; --section-space: 72px; }
  .panel { padding: 40px 24px; border-radius: var(--r-mint); }
  .two-col { grid-template-columns: minmax(0, 1fr); gap: 36px; }
  .preview-header { height: auto; }
  .preview-header .topbar-inner { flex-wrap: wrap; gap: 12px 20px; padding-top: 14px; padding-bottom: 12px; }
  .preview-header .header-tools { margin-left: auto; }
  .preview-header .mainnav { order: 3; width: 100%; margin-left: 0; overflow-x: auto; }
  .preview-header .mainnav li + li::before { margin-inline: 9px; }
}
@media (max-width: 768px) {
  h1 { font-size: clamp(24px, 5.8vw, 30px); }
}
@media (max-width: 640px) {
  .tilt, [data-tilt] { transform: none !important; }
  .card { padding: 24px; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: 32px; }
  .footer-bottom { align-items: flex-start; flex-direction: column; }
  .topbar-inner { gap: 12px; }
  #site-header .brand-name { font-size: 14px; }
  #site-header .brand { gap: 7px; }
  #site-header .lang { padding-inline: 10px; }
  #site-header .lang-full { display: none; }
  #site-header .lang-short { display: inline; }
  #site-header .header-tools { gap: 6px; margin-left: auto; }
  .panel { gap: 28px; }
}
@media (max-width: 360px) {
  #site-header .brand-name { font-size: 12px; }
  #site-header .brand-mark { width: 26px; height: 26px; }
  #site-header .lang svg { display: none; }
  .preview-header .brand-name { font-size: 14px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
  .reveal-ready .reveal:not(.shown) { opacity: 1; transform: none; }
}