:root {
  --bg: #f7f7f6;
  --bg-panel: #ffffff;
  --bg-panel-2: #ebeae8;
  --border: #e2e1de;
  --border-strong: #d4d3cf;
  --accent: #8e2f26;
  --accent-dark: #6b211a;
  --text: #1c1b1a;
  --text-muted: #6b6966;
  --ink-hover: #33312f;
  --success: #2e7d4f;
  --success-ring: rgba(46, 125, 79, 0.16);
  --warn: #6a4bb0;
  --info: #3a63b8;
  --error: #a8322a;
  --on-accent: #ffffff;
  --on-accent-muted: rgba(255, 255, 255, 0.78);
  --on-accent-line: rgba(255, 255, 255, 0.14);
  --on-dark: #f7f7f6;
  --on-dark-muted: rgba(247, 247, 246, 0.72);
  --clear: transparent;
  --veil: rgba(28, 27, 26, 0.32);

  --shadow-soft: 0 1px 2px rgba(28, 27, 26, 0.04);
  --shadow-card: 0 1px 2px rgba(28, 27, 26, 0.04), 0 10px 26px -14px rgba(28, 27, 26, 0.14);
  --shadow-lift: 0 1px 2px rgba(28, 27, 26, 0.05), 0 20px 38px -18px rgba(28, 27, 26, 0.24);
  --shadow-accent: 0 1px 2px rgba(107, 33, 26, 0.22), 0 18px 34px -16px rgba(107, 33, 26, 0.48);
  --shadow-btn: 0 1px 1px rgba(28, 27, 26, 0.18), 0 8px 18px -10px rgba(28, 27, 26, 0.5);

  --radius-small: 2px;
  --radius-focus: 6px;
  --radius-mark: 8px;
  --radius-btn: 10px;
  --radius-shot: 10px;
  --radius-cell: 20px;
  --radius-panel: 28px;
  --radius-panel-mobile: 22px;
  --radius-pill: 999px;
  --radius-round: 50%;
  --radius-quarter: 100% 0 0 0;

  --font-display: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-body: "Inter", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --weight-normal: 400;
  --weight-medium: 500;
  --weight-strong: 600;
  --size-body: 16px;
  --size-small: 13px;
  --size-caption: 12.5px;
  --size-display: clamp(28px, 3.4vw + 8px, 48px);
  --size-h2: clamp(26px, 3vw, 36px);
  --size-h3: 22px;
  --leading-body: 1.6;
  --leading-title: 1.1;
  --tracking-display: -0.02em;
  --tracking-label: 0.14em;

  --container: 1200px;
  --header-container: 1280px;
  --reading-width: 780px;
  --gutter: 40px;
  --section-gap: 140px;
  --header-height: 64px;
  --duration-fast: 160ms;
  --duration-reveal: 450ms;
  --ease-out: cubic-bezier(0.2, 0.7, 0.3, 1);
  --layer-veil: 20;
  --layer-header: 30;
  --layer-popup: 40;
  --layer-fab: 15;
}

*, *::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(--size-body);
  font-weight: var(--weight-normal);
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
[hidden] { display: none !important; }
img, svg { max-width: 100%; }
img { height: auto; }
svg { flex-shrink: 0; }
button, input, select, textarea { font: inherit; }
button, summary, a { -webkit-tap-highlight-color: var(--clear); }
button { cursor: pointer; }
button:disabled { cursor: not-allowed; }
a { color: inherit; text-underline-offset: 4px; }
a:hover { text-decoration-color: var(--accent); }
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: var(--radius-focus);
}
::selection { background: var(--bg-panel-2); color: var(--text); }
h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: var(--weight-normal);
  text-wrap: balance;
  overflow-wrap: break-word;
}
h1 { font-size: var(--size-display); line-height: var(--leading-title); letter-spacing: var(--tracking-display); }
h2 { font-size: var(--size-h2); line-height: 1.2; letter-spacing: var(--tracking-display); }
h3 { font-size: var(--size-h3); line-height: 1.35; }
p, li, dd { overflow-wrap: break-word; }
strong { font-weight: var(--weight-strong); }
code, pre, kbd { font-family: var(--font-mono); }
code { overflow-wrap: anywhere; }
pre {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: var(--radius-btn);
  background: var(--bg-panel-2);
  color: var(--text);
  font-size: var(--size-small);
  line-height: 1.8;
  tab-size: 2;
}
pre code { overflow-wrap: normal; white-space: pre; }
.wrap {
  width: 100%;
  max-width: calc(var(--container) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.reading-wrap { max-width: calc(var(--reading-width) + var(--gutter) * 2); }
.section { padding-top: var(--section-gap); }
.section-last { padding-bottom: var(--section-gap); }
.section-heading { margin-top: 14px; margin-bottom: 24px; }
.word { white-space: nowrap; }
.text-muted { color: var(--text-muted); }
.mono { font-family: var(--font-mono); }
.eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--size-caption);
  letter-spacing: var(--tracking-label);
  text-transform: uppercase;
  color: var(--accent);
}
.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: var(--gutter);
  z-index: var(--layer-popup);
  transform: translateY(-180%);
  padding: 10px 16px;
  background: var(--text);
  color: var(--on-dark);
  border-radius: var(--radius-btn);
}
.skip-link:focus { transform: none; }
.grid-two, .grid-three {
  display: grid;
  gap: 24px;
}
.grid-two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-two > *, .grid-three > *, .wrap > *, .panel > * { min-width: 0; }
.panel, .card {
  border: 1px solid var(--border);
  background: var(--bg-panel);
  color: var(--text);
  box-shadow: var(--shadow-card);
}
.panel { padding: 56px 72px 72px; border-radius: var(--radius-panel); }
.card { padding: 28px; border-radius: var(--radius-cell); }
.card h3 { margin-top: 0; }
.card p { color: var(--text-muted); }
.button, .btn-store {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  min-height: 48px;
  max-width: 100%;
  padding: 10px 22px;
  border: 1px solid var(--text);
  border-radius: var(--radius-btn);
  background: var(--text);
  color: var(--bg-panel);
  font-family: var(--font-body);
  font-size: 15.5px;
  font-weight: var(--weight-medium);
  line-height: 1.4;
  text-decoration: none;
  text-align: center;
  box-shadow: var(--shadow-btn);
}
.button:hover, .btn-store:hover, .button.is-hover {
  background: var(--ink-hover);
  border-color: var(--ink-hover);
  color: var(--bg-panel);
}
.button:active, .button.is-pressed { box-shadow: var(--shadow-soft); }
.button--secondary {
  background: var(--bg-panel);
  color: var(--text);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-soft);
}
.button--secondary:hover { background: var(--bg-panel-2); color: var(--text); border-color: var(--border-strong); }
.button:disabled, .button[aria-disabled="true"] {
  background: var(--bg-panel-2);
  color: var(--text-muted);
  border-color: var(--border);
  box-shadow: none;
}
.link-guide {
  font-size: 15.5px;
  color: var(--text);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 6px;
}
.link-guide:hover { color: var(--accent); }
.btn-store svg { width: 17px; height: 17px; margin-top: -2px; }
.notice-strip {
  background: var(--text);
  color: var(--on-dark-muted);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.notice-strip .wrap {
  min-height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
}
.notice-strip b { color: var(--on-dark); font-weight: var(--weight-medium); }
.notice-sep { width: 3px; height: 3px; flex-shrink: 0; border-radius: var(--radius-round); background: var(--on-dark-muted); }
#site-header { position: relative; z-index: var(--layer-header); }
.masthead { position: relative; border-bottom: 1px solid var(--border); background: var(--bg); color: var(--text); }
.header-wrap {
  position: relative;
  width: 100%;
  max-width: min(100%, calc(var(--header-container) + 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; gap: 11px; text-decoration: none; flex-shrink: 0; }
.brand-mark { display: block; width: 30px; height: 30px; flex-shrink: 0; border-radius: var(--radius-mark); background: var(--bg-panel); color: var(--text); border: 1px solid var(--border); box-shadow: var(--shadow-soft); }
.brand-name { font-size: 15px; font-weight: var(--weight-medium); letter-spacing: -0.01em; }
.desktop-nav { margin-left: auto; min-width: 0; }
.tabbar { display: flex; align-items: center; gap: 2px; list-style: none; margin: 0; padding: 0; }
.tabbar a {
  position: relative;
  display: flex;
  align-items: center;
  min-height: var(--header-height);
  padding: 0 13px;
  color: var(--text-muted);
  font-size: 14.5px;
  text-decoration: none;
  white-space: nowrap;
}
.tabbar a::after {
  content: "";
  position: absolute;
  left: 13px;
  right: 13px;
  bottom: -1px;
  height: 2px;
  border-radius: var(--radius-small);
  background: var(--clear);
}
.tabbar a:hover, .tabbar a[aria-current="page"] { color: var(--text); }
.tabbar a[aria-current="page"]::after { background: var(--text); }
.header-tools { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.language-control { position: relative; }
.lang-switch {
  min-height: 32px;
  padding: 5px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-pill);
  background: var(--bg-panel);
  color: var(--text);
  font-size: var(--size-small);
  white-space: nowrap;
  box-shadow: var(--shadow-soft);
}
.lang-switch .caret { margin-left: 4px; color: var(--text-muted); }
.lang-short { display: none; }
.language-menu {
  position: absolute;
  right: 0;
  top: calc(100% + 10px);
  z-index: var(--layer-popup);
  width: 190px;
  margin: 0;
  padding: 8px;
  list-style: none;
  background: var(--bg-panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius-btn);
  box-shadow: var(--shadow-lift);
}
.language-menu a { display: flex; align-items: center; min-height: 44px; padding: 8px 12px; text-decoration: none; border-radius: var(--radius-focus); }
.language-menu a:hover, .language-menu a[aria-current="true"] { background: var(--bg-panel-2); color: var(--text); }
.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  padding: 10px;
  background: var(--bg-panel);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius-btn);
}
.menu-toggle svg { width: 22px; height: 22px; fill: none; stroke: currentColor; stroke-width: 1.5; }
.mobile-drawer { display: none; }
.nav-veil { position: fixed; inset: 0; z-index: var(--layer-veil); border: 0; background: var(--veil); color: var(--on-dark); }
.hero { padding-top: 44px; padding-bottom: 92px; text-align: center; overflow-x: clip; }
.hero-title { margin: 22px auto 0; color: var(--text); font-size: var(--size-display); line-height: 1.1; letter-spacing: var(--tracking-display); }
.hero-title > span { display: block; }
.cta-row { margin-top: 28px; display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: 26px; }
.hero-lede { margin: 22px auto 0; max-width: 760px; font-size: 16.5px; line-height: 1.7; color: var(--text-muted); }
.hero-lede strong { color: var(--text); font-weight: var(--weight-medium); }
.prose { min-width: 0; }
.prose h2 { margin-top: 64px; margin-bottom: 20px; }
.prose h3 { margin-top: 36px; margin-bottom: 16px; }
.prose p, .prose ul, .prose ol { margin-block: 20px; }
.prose li + li { margin-top: 8px; }
.prose a { text-decoration-thickness: 1px; }
.prose :is(section, article, div) { min-width: 0; }
.prose :is(h2, h3, section)[id] { scroll-margin-top: 24px; }
.reveal { opacity: 1; }
.reveal-enabled .reveal:not(.shown) { opacity: 0; transform: translateY(16px); }
.reveal-enabled .reveal { transition: opacity var(--duration-reveal) var(--ease-out), transform var(--duration-reveal) var(--ease-out); }
.reveal.shown { opacity: 1; transform: none; }
.site-footer { margin-top: var(--section-gap); border-top: 1px solid var(--border); padding-top: 56px; padding-bottom: 32px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 0.8fr 1.4fr 0.8fr; gap: 40px; }
.footer-grid > * { min-width: 0; }
.footer-intro { max-width: 330px; color: var(--text-muted); font-size: 14px; }
.footer-title { margin: 0 0 16px; font-size: 14px; font-weight: var(--weight-medium); }
.footer-links { list-style: none; margin: 0; padding: 0; }
.footer-links a { display: inline-block; padding-block: 5px; color: var(--text-muted); font-size: 13px; text-decoration: none; }
.footer-links a:hover { color: var(--text); text-decoration: underline; }
.footer-bottom { margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--border); display: flex; flex-wrap: wrap; gap: 12px 28px; color: var(--text-muted); font-size: var(--size-caption); }
.footer-bottom p { margin: 0; }
.decorated-region { position: relative; overflow-x: clip; }
@media (max-width: 1279px) {
  .desktop-nav { display: none; }
  .header-tools { margin-left: auto; }
  .menu-toggle { display: inline-flex; }
  .mobile-drawer {
    display: block;
    position: absolute;
    top: 100%;
    left: var(--gutter);
    right: var(--gutter);
    z-index: var(--layer-popup);
    max-height: calc(100dvh - 112px);
    overflow-y: auto;
    overscroll-behavior: contain;
    padding: 16px;
    border: 1px solid var(--border);
    border-radius: var(--radius-cell);
    background: var(--bg-panel);
    color: var(--text);
    box-shadow: var(--shadow-lift);
  }
  .drawer-list { list-style: none; padding: 0; margin: 0; }
  .mobile-drawer a { display: flex; align-items: center; width: 100%; min-height: 44px; padding: 10px 14px; text-decoration: none; border-radius: var(--radius-focus); }
  .mobile-drawer a:hover, .mobile-drawer a[aria-current] { background: var(--bg-panel-2); color: var(--text); }
  .drawer-heading { margin: 16px 14px 6px; padding-top: 16px; border-top: 1px solid var(--border); color: var(--text-muted); font-size: var(--size-small); }
}
@media (max-width: 980px) {
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid-three { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .panel { padding: 40px; }
}
@media (max-width: 768px) {
  :root { --gutter: 20px; --size-display: 28px; }
  h1, .hero-title { font-size: 28px; }
  .notice-strip .wrap { padding-block: 9px; flex-wrap: wrap; gap: 6px 10px; }
  .hero { padding-top: 36px; padding-bottom: 64px; }
  .cta-row { flex-direction: column; gap: 16px; }
  .hero-lede { font-size: 15.5px; }
  .panel { padding: 36px 24px 44px; border-radius: var(--radius-panel-mobile); }
  .header-wrap { gap: 12px; }
}
@media (max-width: 640px) {
  .grid-two, .grid-three, .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .card { padding: 24px; }
  .tilt, [data-tilt], .detail-card--back { transform: none; }
  .lang-long { display: none; }
  .lang-short { display: inline; }
  .section-heading .word { white-space: normal; overflow-wrap: anywhere; }
  .brand-name { min-width: 0; font-size: 13px; overflow-wrap: anywhere; }
  .brand { min-width: 0; flex-shrink: 1; gap: 8px; }
  .brand-mark { width: 28px; height: 28px; }
  .header-tools { gap: 6px; margin-left: auto; }
  .lang-switch { padding-inline: 9px; min-height: 44px; }
  .site-footer { padding-top: 40px; }
}
@media (max-width: 359px) {
  :root { --gutter: 16px; }
  .brand-name { font-size: 11.5px; }
  .header-wrap { gap: 6px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal-enabled .reveal:not(.shown) { opacity: 1; transform: none; }
  .reveal-enabled .reveal { transition: none; }
}