:root {
  --color-bg: #F2F0EB;
  --color-panel: #FAF9F6;
  --color-panel-muted: #E8E5DE;
  --color-border: #D8D3C8;
  --color-accent: #8E3A2E;
  --color-accent-dark: #6B2A21;
  --color-clay: #C97B55;
  --color-moss: #6E8B5B;
  --color-moss-dark: #5B7449;
  --color-slate: #6C86A6;
  --color-slate-dark: #56708F;
  --color-text: #15130F;
  --color-muted: #5F5A50;
  --color-success: #3F7A4E;
  --color-warning: #B27A2A;
  --color-error: #BD2F1E;
  --color-flag-red: #B23A31;
  --color-flag-blue: #3E4F7C;
  --color-flag-white: #F7F5F0;
  --color-paper-72: rgba(242, 240, 235, .72);
  --color-paper-58: rgba(242, 240, 235, .58);
  --color-paper-10: rgba(242, 240, 235, .10);
  --color-white-12: rgba(255, 255, 255, .12);
  --color-white-18: rgba(255, 255, 255, .18);
  --color-white-22: rgba(255, 255, 255, .22);
  --color-ink-06: rgba(21, 19, 15, .06);
  --color-ink-18: rgba(21, 19, 15, .18);
  --color-accent-02: rgba(142, 58, 46, .02);
  --color-accent-05: rgba(142, 58, 46, .05);
  --color-accent-12: rgba(142, 58, 46, .12);
  --color-transparent: rgba(142, 58, 46, 0);
  --font-display: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', -apple-system, 'Segoe UI', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', -apple-system, 'Segoe UI', sans-serif;
  --font-serif: 'Iowan Old Style', 'Palatino Linotype', Palatino, 'Noto Serif CJK SC', 'Songti SC', Georgia, serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', Menlo, Consolas, 'Liberation Mono', monospace;
  --radius-xs: 4px;
  --radius-sm: 8px;
  --radius-card: 22px;
  --radius-pill: 999px;
  --header-height: 68px;
  --content-width: 1440px;
  --reading-width: 760px;
  --gutter: 60px;
  --section-space: 104px;
  --focus-width: 2px;
  --shadow-tint: 0 20px 60px var(--color-accent-12);
  --transition-fast: 150ms ease;
  --transition-reveal: 620ms cubic-bezier(.22, 1, .36, 1);
  --toc-offset: 88px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
}

html,
body {
  margin: 0;
  min-width: 0;
  padding: 0;
}

html.nav-open {
  overflow: hidden;
}

body {
  overflow-x: clip;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img,
svg,
video,
canvas {
  display: block;
  max-width: 100%;
}

img {
  height: auto;
}

button,
input,
select,
textarea {
  color: inherit;
  font: inherit;
}

button,
summary {
  cursor: pointer;
}

a {
  color: inherit;
  text-decoration: none;
}

p,
h1,
h2,
h3,
h4,
ul,
ol,
blockquote,
figure {
  margin-top: 0;
}

ul[role="list"],
ol[role="list"],
.site-nav ul,
.footer-links,
.platform-list,
.flag-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

main,
section,
article,
aside,
nav,
header,
footer,
.wrap,
.grid > *,
.flex > * {
  min-width: 0;
}

.wrap {
  width: 100%;
  max-width: var(--content-width);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.reading-wrap {
  width: 100%;
  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-compact {
  padding-top: 64px;
  padding-bottom: 64px;
}

.section-heading {
  max-width: 840px;
  margin-bottom: 40px;
}

.kicker,
.eyebrow {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0;
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: .06em;
}

.kicker-dot,
.eyebrow .dot,
.status-dot {
  width: 9px;
  height: 9px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--color-accent);
}

h1,
h2,
h3,
h4 {
  color: var(--color-text);
  font-family: var(--font-display);
  text-wrap: balance;
}

h1 {
  font-size: clamp(52px, 5vw, 68px);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -.02em;
}

h2 {
  font-size: clamp(34px, 3.4vw, 52px);
  font-weight: 800;
  line-height: 1.14;
  letter-spacing: -.02em;
}

h3 {
  font-size: clamp(22px, 2vw, 30px);
  font-weight: 750;
  line-height: 1.25;
}

h4 {
  font-size: 18px;
  font-weight: 750;
  line-height: 1.35;
}

.serif {
  font-family: var(--font-serif);
}

.mono {
  font-family: var(--font-mono);
}

.muted {
  color: var(--color-muted);
}

.no-break {
  white-space: nowrap;
}

code,
kbd,
samp {
  font-family: var(--font-mono);
}

:not(pre) > code {
  padding: .15em .4em;
  overflow-wrap: anywhere;
  border-radius: var(--radius-xs);
  background: var(--color-panel-muted);
  font-size: .9em;
}

pre {
  max-width: 100%;
  padding: 20px;
  overflow-x: auto;
  border-radius: var(--radius-sm);
  background: var(--color-text);
  color: var(--color-bg);
  -webkit-overflow-scrolling: touch;
}

pre code {
  white-space: pre;
}

::selection {
  background: var(--color-clay);
  color: var(--color-text);
}

a:focus-visible,
button:focus-visible,
summary:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible,
[role="tab"]:focus-visible {
  outline: var(--focus-width) solid var(--color-accent);
  outline-offset: 3px;
}

.btn {
  display: inline-flex;
  min-width: 24px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 0 22px;
  border: 1px solid var(--color-text);
  border-radius: var(--radius-pill);
  font-size: 15px;
  font-weight: 650;
  line-height: 1;
  white-space: nowrap;
  transition: color var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}

.btn:hover {
  transform: translateY(-1px);
}

.btn svg,
.icon {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
}

.btn-primary,
.btn-ink {
  border-color: var(--color-text);
  background: var(--color-text);
  color: var(--color-bg);
}

.btn-primary:hover,
.btn-ink:hover {
  border-color: var(--color-accent-dark);
  background: var(--color-accent-dark);
}

.btn-secondary,
.btn-ghost {
  background: transparent;
  color: var(--color-text);
}

.btn-secondary:hover,
.btn-ghost:hover {
  background: var(--color-panel-muted);
}

.btn-paper {
  border-color: var(--color-bg);
  background: var(--color-bg);
  color: var(--color-text);
}

.btn-danger {
  border-color: var(--color-error);
  background: var(--color-error);
  color: var(--color-panel);
}

.btn[disabled],
.btn.is-disabled {
  cursor: not-allowed;
  opacity: .48;
  transform: none;
}

.btn-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}

.panel,
.card {
  background: var(--color-panel);
  box-shadow: inset 0 0 0 1px var(--color-white-18), var(--shadow-tint);
}

.panel-muted,
.card-muted {
  background: var(--color-panel-muted);
}

.card {
  padding: 28px;
  border-radius: var(--radius-card);
}

.rule {
  height: 1px;
  border: 0;
  background: var(--color-border);
}

.badge,
.tag,
.fact-pill {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  gap: 7px;
  max-width: 100%;
  padding: 4px 11px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-muted);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 650;
  letter-spacing: .06em;
}

.badge-accent {
  border-color: var(--color-accent);
  background: var(--color-accent);
  color: var(--color-panel);
}

.badge-success {
  border-color: var(--color-success);
  color: var(--color-success);
}

.reveal {
  transition: opacity var(--transition-reveal), transform var(--transition-reveal);
}

.reveal.pending {
  opacity: 0;
  transform: translateY(16px);
}

.reveal.shown {
  opacity: 1;
  transform: none;
}

.site-header {
  position: relative;
  z-index: 100;
  min-height: var(--header-height);
}

.site-head {
  position: relative;
  display: flex;
  min-height: var(--header-height);
  align-items: center;
  gap: 24px;
}

.brand {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}

.brand-mark {
  width: 30px;
  height: 30px;
  flex: 0 0 auto;
}

.brand-en {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  letter-spacing: -.02em;
}

.brand-zh {
  margin-left: -2px;
  color: var(--color-muted);
  font-family: var(--font-serif);
  font-size: 15px;
}

.site-nav {
  margin-left: auto;
}

.site-nav ul {
  display: flex;
  align-items: center;
  gap: 2px;
}

.site-nav a {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  justify-content: center;
  padding: 8px 13px;
  border-radius: var(--radius-pill);
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 550;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.site-nav a:hover {
  color: var(--color-text);
}

.site-nav a[aria-current="page"] {
  background: var(--color-panel-muted);
  color: var(--color-text);
}

.header-tools {
  display: flex;
  align-items: center;
  gap: 8px;
  flex: 0 0 auto;
}

.language-switch {
  position: relative;
}

.language-button,
.menu-toggle {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border: 0;
  border-radius: var(--radius-pill);
  background: transparent;
  color: var(--color-muted);
}

.language-button:hover,
.menu-toggle:hover {
  background: var(--color-panel-muted);
  color: var(--color-text);
}

.language-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 120;
  width: 164px;
  padding: 8px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-panel);
  box-shadow: var(--shadow-tint);
}

.language-menu[hidden] {
  display: none;
}

.language-menu a {
  display: flex;
  min-height: 40px;
  align-items: center;
  padding: 8px 10px;
  border-radius: var(--radius-xs);
  font-size: 13px;
}

.language-menu a:hover,
.language-menu a[aria-current="true"] {
  background: var(--color-panel-muted);
}

.nav-login {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border-radius: var(--radius-pill);
  background: var(--color-text);
  color: var(--color-bg);
  font-size: 14px;
  font-weight: 650;
}

.nav-login:hover {
  background: var(--color-accent-dark);
}

.menu-toggle {
  display: none;
}

.mobile-nav {
  display: none;
}

.mobile-veil {
  display: none;
}

.site-footer {
  overflow-x: clip;
  background: var(--color-text);
  color: var(--color-bg);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.3fr 1fr 1fr .8fr;
  gap: 56px;
  padding-top: 72px;
  padding-bottom: 56px;
}

.footer-brand p {
  max-width: 380px;
  margin: 18px 0 0;
  color: var(--color-paper-72);
}

.footer-title {
  margin-bottom: 16px;
  color: var(--color-paper-58);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .12em;
  text-transform: uppercase;
}

.footer-links {
  display: grid;
  gap: 8px;
}

.footer-links a {
  display: inline-flex;
  min-height: 32px;
  align-items: center;
  color: var(--color-paper-72);
}

.footer-links a:hover {
  color: var(--color-bg);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding-top: 24px;
  padding-bottom: 30px;
  border-top: 1px solid var(--color-white-18);
  color: var(--color-paper-58);
  font-size: 13px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

#server-status {
  position: relative;
  display: block;
  width: 100%;
  margin-bottom: 48px;
  overflow: hidden;
}

[data-counter] {
  display: inline-block;
  min-width: 3.5ch;
  font-variant-numeric: tabular-nums;
  text-align: right;
}

.decor-field,
.hero-visual,
.stripe-halo {
  position: relative;
  max-width: 100%;
  overflow-x: clip;
}

.prose {
  color: var(--color-text);
}

.prose > * {
  max-width: 100%;
}

.prose p,
.prose li {
  overflow-wrap: break-word;
}

.prose h2 {
  margin-top: 72px;
  margin-bottom: 22px;
}

.prose h3 {
  margin-top: 44px;
  margin-bottom: 16px;
}

.prose a:not(.btn) {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: .18em;
}

.prose blockquote {
  margin-inline: 0;
}

body:has(.toc-tabs) section[id] {
  scroll-margin-top: var(--toc-offset);
}

@media (max-width: 1180px) {
  :root {
    --gutter: 36px;
  }

  .site-head {
    gap: 16px;
  }

  .site-nav a {
    padding-inline: 9px;
    font-size: 13px;
  }

  .footer-grid {
    grid-template-columns: 1.4fr 1fr 1fr;
  }

  .footer-language {
    grid-column: 2 / -1;
  }
}

@media (max-width: 900px) {
  :root {
    --gutter: 24px;
    --section-space: 80px;
  }

  .site-nav {
    display: none;
  }

  .header-tools {
    margin-left: auto;
  }

  .language-switch {
    display: none;
  }

  .menu-toggle {
    display: inline-flex;
  }

  .mobile-veil {
    position: fixed;
    inset: 0;
    z-index: 90;
    background: var(--color-ink-18);
  }

  .mobile-veil.is-open {
    display: block;
  }

  .mobile-nav {
    position: absolute;
    top: var(--header-height);
    right: var(--gutter);
    left: var(--gutter);
    z-index: 110;
    max-height: calc(100dvh - var(--header-height) - 16px);
    padding: 12px;
    overflow-y: auto;
    overscroll-behavior: contain;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    background: var(--color-panel);
    box-shadow: var(--shadow-tint);
  }

  .mobile-nav.is-open {
    display: block;
  }

  .mobile-nav ul {
    margin: 0;
    padding: 0;
    list-style: none;
  }

  .mobile-nav a {
    display: flex;
    width: 100%;
    min-height: 46px;
    align-items: center;
    padding: 10px 12px;
    border-radius: var(--radius-xs);
  }

  .mobile-nav a:hover,
  .mobile-nav a[aria-current="page"] {
    background: var(--color-panel-muted);
  }

  .mobile-language {
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid var(--color-border);
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }

  .footer-brand {
    grid-column: 1 / -1;
  }

  .footer-language {
    grid-column: auto;
  }
}

@media (max-width: 768px) {
  :root {
    --gutter: 20px;
    --section-space: 68px;
  }

  h1 {
    font-size: clamp(28px, 10vw, 40px);
    line-height: 1.15;
  }

  h2 {
    font-size: clamp(28px, 8vw, 38px);
  }

  .footer-bottom {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
  }

  .no-break {
    white-space: normal;
  }

  .tilt,
  [class*="tilt-"] {
    transform: none;
  }

  .decor-field,
  .hero-visual,
  .stripe-halo {
    max-width: 100%;
  }

  .btn-row {
    align-items: stretch;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 36px;
  }

  .footer-brand,
  .footer-language {
    grid-column: auto;
  }

  .brand-en {
    font-size: 17px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0s !important;
  }

  .reveal,
  .reveal.pending,
  .reveal.shown {
    opacity: 1;
    transform: none;
  }
}