:root {
  --color-canvas: #FFFFFF;
  --color-panel: #FAFBFB;
  --color-panel-strong: #F3F5F4;
  --color-line: #E3E6E5;
  --color-accent: #0B5F58;
  --color-accent-deep: #07423D;
  --color-ink: #101413;
  --color-ink-muted: #5D6563;
  --color-success: #1C7C43;
  --color-warning: #B07C1E;
  --color-error: #C2402F;
  --color-flag-red: #C63C36;
  --color-flag-blue: #2C4E9C;
  --color-flag-gold: #E0B23C;
  --color-flag-dark: #26292B;
  --color-white: #FFFFFF;
  --color-shadow: rgba(16, 20, 19, 0.07);
  --color-accent-soft: rgba(11, 95, 88, 0.12);
  --color-accent-faint: rgba(11, 95, 88, 0.06);
  --color-overlay: rgba(16, 20, 19, 0.34);
  --font-display: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, 'SF Mono', Consolas, 'Courier New', monospace;
  --radius-xs: 4px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-pill: 999px;
  --shadow-menu: 0 10px 28px var(--color-shadow);
  --content-width: 1200px;
  --reading-width: 900px;
  --header-height: 64px;
  --gutter: clamp(16px, 3vw, 28px);
  --section-space: clamp(64px, 9vw, 112px);
  --toc-offset: 76px;
  --ease-standard: 180ms ease;
}

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

html {
  scroll-behavior: smooth;
  background: var(--color-canvas);
}

html.nav-open {
  overflow: hidden;
}

body {
  margin: 0;
  min-width: 320px;
  overflow-x: clip;
  background: var(--color-canvas);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

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

img {
  height: auto;
}

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

button {
  cursor: pointer;
}

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

ul,
ol {
  margin-top: 0;
}

ul[role='list'],
ol[role='list'],
.site-nav-list,
.footer-list,
.language-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

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

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

h1 {
  margin-bottom: 20px;
  font-size: clamp(52px, 6vw, 72px);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(30px, 4vw, 44px);
  font-weight: 850;
  letter-spacing: -0.02em;
  line-height: 1.16;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2.5vw, 27px);
  font-weight: 750;
  line-height: 1.25;
}

p {
  margin-bottom: 1em;
}

strong {
  font-weight: 700;
}

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

code {
  overflow-wrap: anywhere;
}

pre {
  max-width: 100%;
  overflow-x: auto;
  padding: 18px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-ink);
  color: var(--color-white);
  -webkit-overflow-scrolling: touch;
}

::selection {
  background: var(--color-accent-soft);
  color: var(--color-ink);
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

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

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

.section {
  padding-top: var(--section-space);
  padding-bottom: var(--section-space);
}

.section-compact {
  padding-top: clamp(40px, 6vw, 72px);
  padding-bottom: clamp(40px, 6vw, 72px);
}

.section-head {
  max-width: 720px;
  margin-bottom: 38px;
}

.section-head.is-centered {
  margin-inline: auto;
  text-align: center;
}

.eyebrow,
.mono-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.eyebrow {
  margin-bottom: 12px;
  color: var(--color-accent);
}

.mono-label {
  color: var(--color-ink-muted);
}

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

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

.panel,
.card {
  min-width: 0;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-panel);
}

.panel {
  padding: clamp(20px, 3vw, 32px);
}

.card {
  padding: 24px;
}

.grid {
  display: grid;
  gap: 20px;
}

.grid > * {
  min-width: 0;
}

.grid-two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-three {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

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

.cluster > svg,
.cluster > img,
.icon,
.dot {
  flex-shrink: 0;
}

.badge,
.tag,
.trust-chip {
  display: inline-flex;
  max-width: 100%;
  align-items: center;
  gap: 7px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-canvas);
  color: var(--color-ink-muted);
  line-height: 1.35;
}

.badge,
.tag {
  min-height: 28px;
  padding: 5px 11px;
  overflow: hidden;
  font-size: 12px;
}

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

.status-dot {
  width: 7px;
  height: 7px;
  flex-shrink: 0;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-soft);
}

.btn {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0 30px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-canvas);
  color: var(--color-ink);
  font-weight: 700;
  line-height: 1;
  text-align: center;
  transition: background var(--ease-standard), border-color var(--ease-standard), color var(--ease-standard);
}

.btn:hover {
  border-color: var(--color-ink-muted);
  background: var(--color-panel);
}

.btn-primary {
  border-color: var(--color-accent);
  background: var(--color-accent);
  color: var(--color-white);
}

.btn-primary:hover {
  border-color: var(--color-accent-deep);
  background: var(--color-accent-deep);
  color: var(--color-white);
}

.btn-secondary {
  border-color: var(--color-ink);
}

.btn-small {
  min-height: 40px;
  padding-inline: 18px;
  font-size: 14px;
}

.btn[aria-disabled='true'],
.btn:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.site-head {
  position: relative;
  z-index: 100;
  height: var(--header-height);
  border-bottom: 1px solid var(--color-line);
  background: var(--color-canvas);
}

html.nav-open .site-head {
  z-index: 120;
}

.head-inner {
  position: relative;
  z-index: 101;
  display: flex;
  width: 100%;
  max-width: var(--content-width);
  height: 100%;
  align-items: center;
  gap: 28px;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.brand {
  display: inline-flex;
  flex-shrink: 0;
  align-items: center;
  gap: 9px;
}

.brand-mark {
  width: 29px;
  height: 29px;
  flex-shrink: 0;
}

.brand-name {
  color: var(--color-ink);
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.brand-local {
  color: var(--color-ink-muted);
  font-weight: 500;
}

.desktop-nav {
  display: flex;
  align-items: center;
}

.site-nav-list {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link,
.nav-more-button {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  gap: 6px;
  padding: 7px 12px;
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-ink-muted);
  font-size: 14px;
  font-weight: 500;
  white-space: nowrap;
}

.nav-link:hover,
.nav-more-button:hover {
  background: var(--color-panel-strong);
  color: var(--color-ink);
}

.nav-link.is-active,
.nav-more.is-active > .nav-more-button {
  color: var(--color-ink);
  font-weight: 700;
}

.nav-more {
  position: relative;
}

.nav-caret {
  width: 10px;
  height: 10px;
}

.nav-drop,
.language-menu {
  position: absolute;
  top: calc(100% + 6px);
  z-index: 105;
  display: none;
  min-width: 170px;
  padding: 6px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-canvas);
  box-shadow: var(--shadow-menu);
}

.nav-drop {
  left: 0;
}

.nav-more:hover .nav-drop,
.nav-more:focus-within .nav-drop,
.nav-more.is-open .nav-drop {
  display: block;
}

.nav-drop a,
.language-menu a {
  display: flex;
  width: 100%;
  min-height: 40px;
  align-items: center;
  padding: 8px 11px;
  border-radius: var(--radius-sm);
  color: var(--color-ink-muted);
  font-size: 14px;
}

.nav-drop a:hover,
.language-menu a:hover,
.language-menu a[aria-current='true'] {
  background: var(--color-panel-strong);
  color: var(--color-ink);
}

.header-tools {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-left: auto;
}

.language-picker {
  position: relative;
}

.language-button {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  gap: 6px;
  padding: 7px 9px;
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-ink-muted);
  font-size: 13px;
}

.language-button:hover {
  background: var(--color-panel-strong);
  color: var(--color-ink);
}

.language-picker.is-open .language-menu {
  right: 0;
  display: block;
}

.header-login {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  justify-content: center;
  padding: 7px 19px;
  border: 1px solid var(--color-ink);
  border-radius: var(--radius-sm);
  background: var(--color-canvas);
  color: var(--color-ink);
  font-size: 14px;
  font-weight: 700;
}

.header-login:hover {
  background: var(--color-ink);
  color: var(--color-white);
}

.menu-toggle {
  display: none;
  width: 44px;
  min-width: 44px;
  height: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  padding: 0;
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
}

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  width: 19px;
  height: 1px;
  background: var(--color-ink);
}

.menu-toggle-lines {
  position: relative;
}

.menu-toggle-lines::before,
.menu-toggle-lines::after {
  position: absolute;
  left: 0;
  content: '';
}

.menu-toggle-lines::before {
  top: -6px;
}

.menu-toggle-lines::after {
  top: 6px;
}

.mobile-nav {
  position: fixed;
  top: var(--header-height);
  right: 0;
  left: 0;
  z-index: 110;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  overflow-y: auto;
  padding: 10px var(--gutter) 18px;
  border-bottom: 1px solid var(--color-line);
  background: var(--color-canvas);
  overscroll-behavior: contain;
}

.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: 11px 8px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-ink-muted);
}

.mobile-nav a.is-active {
  color: var(--color-accent);
  font-weight: 700;
}

.mobile-language-title {
  margin: 18px 8px 4px;
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.12em;
}

.nav-veil {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 90;
  display: none;
  border: 0;
  background: var(--color-overlay);
}

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

.site-footer {
  border-top: 1px solid var(--color-line);
  background: var(--color-panel);
}

.footer-main {
  display: grid;
  grid-template-columns: minmax(220px, 1.35fr) repeat(3, minmax(150px, 1fr));
  gap: 42px;
  padding-top: 58px;
  padding-bottom: 48px;
}

.footer-brand p {
  max-width: 340px;
  margin-top: 16px;
  color: var(--color-ink-muted);
}

.footer-title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.footer-list {
  display: grid;
  gap: 9px;
}

.footer-list a {
  color: var(--color-ink-muted);
  font-size: 14px;
}

.footer-list a:hover {
  color: var(--color-accent);
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 14px;
  padding-top: 20px;
  padding-bottom: 24px;
  border-top: 1px solid var(--color-line);
  color: var(--color-ink-muted);
  font-size: 13px;
}

.reveal {
  transition: opacity 560ms ease, transform 560ms ease;
}

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

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

.tilt,
.tilt-card {
  transform: rotate(-0.45deg);
}

.prose {
  min-width: 0;
}

.prose p,
.prose li {
  color: var(--color-ink-muted);
}

.prose h2,
.prose h3 {
  scroll-margin-top: var(--toc-offset);
}

.prose blockquote {
  margin-inline: 0;
}

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

@media (max-width: 960px) {
  .desktop-nav,
  .desktop-language {
    display: none;
  }

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

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

  .footer-main {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 768px) {
  h1 {
    font-size: clamp(28px, 9.4vw, 40px);
    line-height: 1.12;
  }

  h2 {
    font-size: clamp(27px, 7vw, 36px);
  }

  .grid-two,
  .grid-three {
    grid-template-columns: minmax(0, 1fr);
  }

  .header-tools {
    gap: 4px;
  }

  .header-login {
    min-height: 36px;
    padding-inline: 13px;
  }

  .footer-main {
    gap: 32px 20px;
  }
}

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

  body {
    overflow-x: clip;
  }

  .wrap,
  .reading-wrap {
    padding-inline: var(--gutter);
  }

  .section,
  .section-compact {
    padding-right: 0;
    padding-left: 0;
  }

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

  .btn {
    padding-inline: 22px;
  }

  .language-button {
    display: none;
  }

  .footer-main {
    grid-template-columns: minmax(0, 1fr);
  }

  .footer-bottom {
    flex-direction: column;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }

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