:root {
  --c-bg: #FEFEFB;
  --c-panel: #F7F6F2;
  --c-panel-2: #EFEEE9;
  --c-border: #E4E2DC;
  --c-border-strong: #D5D2CA;
  --c-accent: #F25C05;
  --c-accent-dark: #C24904;
  --c-text: #1E1B16;
  --c-muted: #625E56;
  --c-faint: #8E897F;
  --c-success: #2F8A57;
  --c-warn: #B9781A;
  --c-error: #C2362B;
  --c-white: #FFFFFF;
  --c-on-accent: #FFFFFF;
  --c-field-sage: #D6DCD3;
  --c-field-mist: #ECEDE7;
  --c-field-sand: #E4DDD1;
  --c-field-dot: rgba(98, 94, 86, 0.16);
  --c-ring: rgba(47, 138, 87, 0.45);
  --c-veil: rgba(30, 27, 22, 0.24);
  --c-clear: transparent;
  --mask-ink: #000000;
  --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;
  --r-ctl: 4px;
  --r-card: 8px;
  --r-field: 6px;
  --r-pill: 999px;
  --r-circle: 50%;
  --shadow-hair: 0 2px 2px rgba(30, 27, 22, 0.05);
  --shadow-window: 0 1px 0 rgba(30, 27, 22, 0.03), 0 2px 3px rgba(30, 27, 22, 0.06);
  --w-shell: 1280px;
  --w-content: 1120px;
  --w-reading: 800px;
  --h-header: 60px;
  --gutter: 32px;
  --space-section: 104px;
  --text-base: 15px;
  --text-h1: clamp(34px, 2vw + 20px, 48px);
  --text-h2: 32px;
  --text-h3: 24px;
  --weight-normal: 400;
  --weight-display: 440;
  --weight-medium: 520;
  --weight-strong: 560;
  --tracking-display: -0.035em;
  --tracking-cjk: -0.02em;
  --ease-ui: 150ms ease;
  --ease-reveal: 500ms ease;
  --z-header: 60;
  --z-fab: 30;
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 80px; }
html.nav-open { overflow: hidden; }
body {
  margin: 0;
  background: var(--c-bg);
  color: var(--c-text);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
button, input, select, textarea { color: var(--c-text); }
button { background: var(--c-bg); }
img { display: block; max-width: 100%; height: auto; }
svg { display: block; flex-shrink: 0; }
button svg, a svg { width: 16px; height: 16px; }
[hidden] { display: none !important; }
:focus-visible { outline: 2px solid var(--c-accent-dark); outline-offset: 3px; border-radius: var(--r-ctl); }
::selection { background: var(--c-panel-2); color: var(--c-text); }
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: var(--weight-display); text-wrap: balance; }
h1 { font-size: var(--text-h1); line-height: 1.12; letter-spacing: var(--tracking-cjk); }
h2 { font-size: var(--text-h2); line-height: 1.25; letter-spacing: var(--tracking-cjk); }
h3 { font-size: var(--text-h3); line-height: 1.35; letter-spacing: var(--tracking-cjk); }
p { margin: 0 0 1em; }
strong { font-weight: var(--weight-strong); }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; font-size: .9em; }
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 20px;
  border: 1px solid var(--c-border);
  border-radius: var(--r-ctl);
  background: var(--c-panel);
  color: var(--c-text);
  line-height: 1.7;
  -webkit-overflow-scrolling: touch;
}
pre code { overflow-wrap: normal; white-space: pre; font-size: 13px; }
hr { border: 0; border-top: 1px solid var(--c-border); margin-block: 32px; }
.wrap {
  width: 100%;
  max-width: calc(var(--w-content) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
  min-width: 0;
}
.reading { max-width: calc(var(--w-reading) + var(--gutter) * 2); }
.section { padding-top: var(--space-section); padding-bottom: var(--space-section); }
.grid-two { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 24px; }
.grid-two > *, .prose, .prose > *, .card > *, .panel > * { min-width: 0; }
.prose { line-height: 1.85; }
.prose h2 { margin-top: 2.4em; margin-bottom: .7em; scroll-margin-top: 80px; }
.prose h3 { margin-top: 1.8em; margin-bottom: .6em; }
.prose a:not(.btn) { text-decoration: underline; text-underline-offset: 4px; }
.prose ul, .prose ol { padding-left: 1.5em; }
.prose li + li { margin-top: .5em; }
.prose code:not(pre code) { background: var(--c-panel); color: var(--c-text); padding: 2px 5px; border-radius: var(--r-ctl); }
.keep-word { white-space: nowrap; }
.muted { color: var(--c-muted); }
.small { font-size: 13px; }
.mono { font-family: var(--font-mono); }
.hl { color: var(--c-accent); }
.eyebrow { font-size: 12px; letter-spacing: .12em; color: var(--c-muted); }
.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: fixed; top: 8px; left: 16px; z-index: 100;
  padding: 10px 16px; background: var(--c-bg); color: var(--c-text);
  border: 1px solid var(--c-border); border-radius: var(--r-ctl);
  transform: translateY(-160%);
}
.skip-link:focus { transform: none; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 44px; padding: 0 22px; max-width: 100%;
  border: 1px solid var(--c-border-strong); border-radius: var(--r-ctl);
  font-size: 15.5px; font-weight: var(--weight-medium); letter-spacing: -.005em;
  line-height: 1.4; text-align: center;
  background: var(--c-bg); color: var(--c-text);
  transition: background-color var(--ease-ui), border-color var(--ease-ui), color var(--ease-ui);
}
.btn-primary { background: var(--c-accent); color: var(--c-on-accent); border-color: var(--c-accent); }
.btn-primary:hover, .btn-primary.is-hover { background: var(--c-accent-dark); color: var(--c-on-accent); border-color: var(--c-accent-dark); }
.btn-primary:active, .btn-primary.is-pressed { background: var(--c-accent-dark); color: var(--c-on-accent); border-color: var(--c-text); }
.btn-outline { background: var(--c-bg); color: var(--c-text); border-color: var(--c-text); }
.btn-outline:hover, .btn-outline.is-hover { background: var(--c-panel); color: var(--c-text); }
.btn-outline:active { background: var(--c-panel-2); color: var(--c-text); }
.btn-quiet { background: var(--c-panel); color: var(--c-text); border-color: var(--c-border); }
.btn-quiet:hover { background: var(--c-panel-2); color: var(--c-text); }
.btn:disabled, .btn[aria-disabled="true"] {
  background: var(--c-panel-2); color: var(--c-muted); border-color: var(--c-border);
  cursor: not-allowed;
}
.btn.is-focus { outline: 2px solid var(--c-accent-dark); outline-offset: 3px; }
.button-row { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.card, .panel {
  min-width: 0; padding: 28px;
  border: 1px solid var(--c-border); border-radius: var(--r-card);
  background: var(--c-panel); color: var(--c-text);
}
.card h3 { margin-top: 0; }
.card p:last-child, .panel p:last-child { margin-bottom: 0; }
.card-mark {
  display: block; width: 10px; height: 10px; margin-bottom: 24px;
  background: var(--c-accent); color: var(--c-text); flex-shrink: 0;
}

/* 独立页头版心不复用正文版心。 */
.masthead { position: relative; z-index: var(--z-header); height: var(--h-header); border-bottom: 1px solid var(--c-border); background: var(--c-bg); color: var(--c-text); }
.masthead-inner {
  position: relative; z-index: 1;
  max-width: min(100%, calc(var(--w-shell) + var(--gutter) * 2));
  height: 100%; margin-inline: auto; padding-inline: var(--gutter);
  display: flex; align-items: center; gap: 36px;
}
.brand {
  display: inline-flex; align-items: center; gap: 10px; flex-shrink: 0;
  font-size: 16px; font-weight: var(--weight-strong); letter-spacing: -.01em;
  color: var(--c-text); white-space: nowrap;
}
.brand-mark { width: 28px; height: 28px; flex-shrink: 0; }
.primary-nav { flex: 1; min-width: 0; }
.nav-list { display: flex; align-items: center; gap: 2px; margin: 0; padding: 0; list-style: none; }
.nav-list li { min-width: 0; }
.nav-link {
  display: inline-flex; align-items: center; gap: 7px;
  min-height: 36px; padding: 0 11px; border-radius: var(--r-ctl);
  font-size: 14.5px; color: var(--c-muted); white-space: nowrap;
  transition: color var(--ease-ui), background-color var(--ease-ui);
}
.nav-link svg { width: 16px; height: 16px; color: var(--c-faint); }
.nav-link:hover { background: var(--c-panel); color: var(--c-text); }
.nav-link:hover svg { color: var(--c-muted); }
.nav-link[aria-current="page"] { color: var(--c-text); font-weight: var(--weight-medium); }
.nav-link[aria-current="page"] svg { color: var(--c-accent); }
.header-tools { display: flex; align-items: center; gap: 8px; flex-shrink: 0; margin-left: auto; }
.language-box { position: relative; }
.lang-switch {
  display: inline-flex; align-items: center; gap: 7px; min-height: 34px;
  padding: 0 12px; border: 1px solid var(--c-border); border-radius: var(--r-ctl);
  font-size: 13.5px; color: var(--c-muted); background: var(--c-bg);
  white-space: nowrap;
}
.lang-switch svg { width: 15px; height: 15px; }
.lang-caret { font-size: 10px; color: var(--c-muted); }
.lang-short { display: none; }
.language-menu {
  position: absolute; right: 0; top: calc(100% + 10px);
  min-width: 180px; padding: 6px; margin: 0; list-style: none;
  border: 1px solid var(--c-border); border-radius: var(--r-card);
  background: var(--c-bg); color: var(--c-text); box-shadow: var(--shadow-hair);
}
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 8px 12px; border-radius: var(--r-ctl); }
.language-menu a:hover { background: var(--c-panel); color: var(--c-text); }
.language-menu a[aria-current="true"] { color: var(--c-accent-dark); }
.menu-toggle { display: none; align-items: center; justify-content: center; min-width: 44px; min-height: 44px; padding: 8px; border: 1px solid var(--c-border); border-radius: var(--r-ctl); background: var(--c-bg); color: var(--c-text); }
.menu-toggle svg { width: 20px; height: 20px; }
.mobile-drawer { display: none; }
.menu-veil { position: fixed; inset: var(--h-header) 0 0; z-index: 0; border: 0; background: var(--c-veil); color: var(--c-text); cursor: pointer; }

/* 拍板首屏：自然内容高，无全屏底部空墙。 */
.hero { padding: 24px var(--gutter) 0; text-align: center; overflow-x: clip; }
.hero-tag {
  display: inline-flex; align-items: center; gap: 9px; max-width: 100%;
  padding: 5px 13px 5px 11px; border: 1px solid var(--c-border); border-radius: var(--r-pill);
  background: var(--c-bg); color: var(--c-muted); font-size: 13px; line-height: 1.4; letter-spacing: .06em;
}
.pulse-dot { position: relative; width: 7px; height: 7px; flex-shrink: 0; border-radius: var(--r-circle); background: var(--c-success); color: var(--c-text); }
.hero-title {
  margin: 14px auto 0; font-family: var(--font-display);
  font-size: clamp(28px, 2vw + 20px, 48px); font-weight: var(--weight-display);
  line-height: 1.12; letter-spacing: var(--tracking-display); color: var(--c-text);
}
.hero-title .sep { color: var(--c-faint); font-weight: 300; padding: 0 .12em; }
.hero-actions { display: flex; justify-content: center; gap: 12px; margin-top: 18px; }
.hero-lede { margin: 14px auto 0; max-width: 760px; font-size: 16px; line-height: 1.6; color: var(--c-muted); }
.hero-lede strong { color: var(--c-text); font-weight: var(--weight-strong); }
.chip-row, .platform-row { display: flex; justify-content: center; align-items: center; flex-wrap: wrap; }
.chip-row { gap: 8px; margin-top: 12px; }
.row-label { font-size: 12px; letter-spacing: .12em; color: var(--c-faint); margin-right: 6px; }
.chip {
  display: inline-flex; align-items: center; max-width: 100%; padding: 3px 11px;
  border: 1px solid var(--c-border); border-radius: var(--r-pill);
  background: var(--c-panel); color: var(--c-muted); font-family: var(--font-mono);
  font-size: 12.5px; line-height: 1.4; overflow-wrap: anywhere;
}
.platform-row { gap: 22px; margin-top: 12px; }
.platform-row .row-label { margin-right: -10px; }
.platform-link { display: inline-flex; align-items: center; gap: 7px; font-size: 13.5px; line-height: 20px; color: var(--c-muted); }
.platform-link svg { width: 15px; height: 15px; color: var(--c-text); opacity: .72; }
.platform-link:hover { color: var(--c-text); }
.platform-link:hover svg { opacity: 1; }
.fact-band { display: flex; justify-content: center; margin: 20px auto 0; padding: 0; list-style: none; }
.fact { min-width: 232px; padding: 0 28px; border-left: 1px solid var(--c-border); }
.fact:first-child { border-left: 0; }
.fact-num { display: block; font-family: var(--font-display); font-size: 22px; font-weight: 420; line-height: 1.2; letter-spacing: -.02em; color: var(--c-accent); }
.fact-note { display: block; margin-top: 4px; font-size: 12.5px; line-height: 1.4; color: var(--c-muted); }
.next { padding-top: 104px; padding-bottom: 120px; text-align: center; }
.next-title { margin: 0; font-family: var(--font-display); font-size: 32px; font-weight: 420; line-height: 1.25; letter-spacing: -.03em; }
.next-lede { max-width: 720px; margin: 14px auto 0; font-size: 16px; color: var(--c-muted); }

/* 页脚 */
.site-footer { margin-top: 64px; padding-top: 52px; padding-bottom: 24px; border-top: 1px solid var(--c-border); background: var(--c-panel); color: var(--c-text); }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1.4fr 1fr; gap: 36px; }
.footer-grid > * { min-width: 0; }
.footer-brand p { margin-top: 16px; max-width: 320px; font-size: 14px; color: var(--c-muted); }
.footer-heading { margin: 0 0 12px; font-size: 14px; font-weight: var(--weight-strong); }
.footer-links { margin: 0; padding: 0; list-style: none; }
.footer-links a { display: inline-block; padding-block: 5px; font-size: 13px; color: var(--c-muted); }
.footer-links a:hover { color: var(--c-accent-dark); text-decoration: underline; text-underline-offset: 3px; }
.footer-bottom { display: flex; align-items: center; flex-wrap: wrap; justify-content: space-between; gap: 16px; margin-top: 36px; padding-top: 20px; border-top: 1px solid var(--c-border); font-size: 13px; color: var(--c-muted); }
.footer-bottom p { margin: 0; }

/* 无脚本时默认可见，观察器脚本启用后才淡入。 */
.reveal { opacity: 1; transform: none; }
.reveal-ready .reveal { opacity: 0; transform: translateY(12px); transition: opacity var(--ease-reveal), transform var(--ease-reveal); }
.reveal-ready .reveal.shown { opacity: 1; transform: none; }

@media (max-width: 1100px) {
  .masthead-inner { gap: 20px; }
  .primary-nav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .mobile-drawer:not([hidden]) {
    display: block; position: fixed; z-index: 3; inset: var(--h-header) 0 auto;
    max-height: calc(100dvh - var(--h-header)); overflow-y: auto; overscroll-behavior: contain;
    padding: 16px var(--gutter) 24px; background: var(--c-bg); color: var(--c-text);
    border-bottom: 1px solid var(--c-border);
  }
  .mobile-drawer .nav-list { display: block; }
  .mobile-drawer .nav-link, .mobile-drawer .drawer-language {
    display: flex; align-items: center; width: 100%; min-height: 44px; padding: 10px 12px;
  }
  .drawer-languages { padding-top: 12px; margin-top: 12px; border-top: 1px solid var(--c-border); }
  .drawer-language { font-size: 14px; border-radius: var(--r-ctl); }
  .drawer-language:hover { background: var(--c-panel); color: var(--c-text); }
  .drawer-language[aria-current="true"] { color: var(--c-accent-dark); }
}
@media (max-width: 920px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .fact { min-width: 0; padding-inline: 16px; }
}
@media (max-width: 768px) {
  h1, .hero-title { font-size: clamp(24px, 4vw, 30px); letter-spacing: var(--tracking-cjk); }
}
@media (max-width: 640px) {
  :root { --gutter: 20px; --space-section: 64px; --text-h2: 26px; --text-h3: 22px; }
  .masthead-inner { gap: 8px; }
  .brand { font-size: 14px; gap: 8px; }
  .header-tools { margin-left: auto; gap: 6px; }
  .lang-full { display: none; }
  .lang-short { display: inline; }
  .lang-switch { padding-inline: 9px; min-height: 44px; }
  .lang-switch svg { display: none; }
  .grid-two, .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .card, .panel { padding: 22px; }
  .hero { padding-top: 28px; }
  .hero-actions { flex-direction: column; align-items: stretch; }
  .hero-title .keep-word { white-space: normal; }
  .hero-tag { letter-spacing: 0; font-size: 12px; }
  .platform-row { gap: 14px; }
  .platform-row .row-label { flex-basis: 100%; margin: 0; }
  .fact-band { flex-wrap: wrap; gap: 14px 0; }
  .fact { flex: 1 1 50%; padding-inline: 8px; }
  .fact:last-child { flex-basis: 100%; border-left: 0; }
  .fact-num { font-size: 20px; }
  .next-title { font-size: 24px; letter-spacing: var(--tracking-cjk); }
  .next { padding-top: 72px; padding-bottom: 64px; }
  .tilt, .sheet-back { transform: none !important; }
  .site-footer { padding-bottom: 28px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; animation: none !important; }
  .reveal-ready .reveal { opacity: 1; transform: none; }
}