:root {
  --color-page: #F0F0F0;
  --color-panel: #FFFFFF;
  --color-panel-muted: #E7E7E9;
  --color-line: #DBDBDE;
  --color-accent: #C81D53;
  --color-accent-strong: #A11342;
  --color-ink: #17171A;
  --color-ink-muted: #5F5F66;
  --color-success: #1E8E5A;
  --color-warning: #C07A12;
  --color-error: #C93A2E;
  --color-focus: #C81D53;
  --color-overlay: rgba(23, 23, 26, .42);
  --color-shadow-soft: rgba(23, 23, 26, .05);
  --color-shadow: rgba(23, 23, 26, .07);
  --color-shadow-deep: rgba(23, 23, 26, .10);
  --color-accent-ring: rgba(200, 29, 83, .15);
  --color-accent-glow: rgba(200, 29, 83, .50);
  --color-flag-red: #CE3B34;
  --color-flag-blue: #33518F;
  --color-flag-green: #37934F;
  --color-flag-white: #FFFFFF;
  --color-flag-gold: #E5B643;
  --color-footer: #17171A;
  --color-footer-text: #FFFFFF;
  --color-footer-muted: #B9B9BF;
  --font-display: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, 'Cascadia Mono', Consolas, monospace;
  --radius-xs: 6px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-pill: 999px;
  --shadow-low: 0 1px 2px var(--color-shadow-soft), 0 10px 26px var(--color-shadow);
  --shadow-high: 0 2px 4px var(--color-shadow), 0 16px 34px var(--color-shadow-deep);
  --header-height: 64px;
  --content-max: 1240px;
  --wide-max: 1376px;
  --text-max: 760px;
  --gutter: clamp(16px, 4vw, 32px);
  --section-space: clamp(64px, 9vw, 112px);
  --transition-fast: 150ms ease;
  --transition-normal: 260ms ease;
}

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

html {
  min-width: 320px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
  text-size-adjust: 100%;
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  margin: 0;
  overflow-x: clip;
  background: var(--color-page);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

main,
header,
footer,
section,
article,
aside,
nav,
div {
  min-width: 0;
}

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

img {
  height: auto;
}

svg {
  flex-shrink: 0;
}

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

button,
summary {
  cursor: pointer;
}

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

p,
ul,
ol,
blockquote,
pre,
table {
  margin-top: 0;
}

p:last-child,
ul:last-child,
ol:last-child,
blockquote:last-child {
  margin-bottom: 0;
}

h1,
h2,
h3,
h4 {
  margin-top: 0;
  color: var(--color-ink);
  font-family: var(--font-display);
  text-wrap: balance;
}

h1 {
  font-size: clamp(52px, 5vw, 72px);
  font-weight: 900;
  letter-spacing: -.02em;
  line-height: 1.1;
}

h2 {
  font-size: clamp(32px, 4vw, 48px);
  font-weight: 900;
  letter-spacing: -.018em;
  line-height: 1.15;
}

h3 {
  font-size: clamp(20px, 2vw, 26px);
  font-weight: 800;
  line-height: 1.25;
}

strong {
  font-weight: 750;
}

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

code {
  overflow-wrap: anywhere;
}

pre {
  max-width: 100%;
  overflow-x: auto;
  padding: 20px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-panel);
  -webkit-overflow-scrolling: touch;
}

pre code {
  overflow-wrap: normal;
  white-space: pre;
}

table {
  border-collapse: collapse;
}

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

:where(a, button, input, select, textarea, summary, [tabindex]):focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
}

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

.wrap {
  width: 100%;
  max-width: calc(var(--content-max) + var(--gutter) * 2);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.wrap-wide {
  max-width: calc(var(--wide-max) + var(--gutter) * 2);
}

.text-wrap {
  max-width: var(--text-max);
}

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

.section-compact {
  padding-top: calc(var(--section-space) * .65);
  padding-bottom: calc(var(--section-space) * .65);
}

.section-head {
  max-width: 760px;
  margin-bottom: 36px;
}

.section-kicker {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  margin-bottom: 12px;
  padding: 4px 10px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .08em;
}

.lead {
  color: var(--color-ink-muted);
  font-size: clamp(17px, 2vw, 21px);
  line-height: 1.65;
}

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

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

.panel,
.card {
  border-radius: var(--radius-lg);
  background: var(--color-panel);
  box-shadow: var(--shadow-low);
}

.panel {
  padding: clamp(22px, 4vw, 40px);
}

.card {
  padding: 24px;
}

.card-outline {
  border: 1px solid var(--color-line);
  box-shadow: none;
}

.card-muted {
  background: var(--color-panel-muted);
  box-shadow: none;
}

.badge,
.tag,
.fact-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 26px;
  max-width: 100%;
  padding: 4px 10px;
  overflow: hidden;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.4;
  text-overflow: ellipsis;
  white-space: nowrap;
}

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

.status-dot {
  width: 8px;
  height: 8px;
  flex: 0 0 8px;
  border-radius: 50%;
  background: var(--color-success);
}

.btn,
.btn-primary,
.btn-secondary,
.btn-ghost,
.btn-login {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  padding: 11px 24px;
  font-weight: 700;
  line-height: 1.2;
  text-align: center;
  transition: border-color var(--transition-fast), background-color var(--transition-fast), color var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn:hover,
.btn-primary:hover,
.btn-secondary:hover,
.btn-ghost:hover,
.btn-login:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--color-accent);
  color: var(--color-panel);
  box-shadow: 0 6px 16px var(--color-accent-ring);
}

.btn-primary:hover {
  background: var(--color-accent-strong);
}

.btn-secondary,
.btn-ghost,
.btn-login {
  border-color: var(--color-line);
  background: var(--color-panel);
  color: var(--color-ink);
}

.btn-secondary:hover,
.btn-ghost:hover,
.btn-login:hover {
  border-color: var(--color-ink-muted);
  box-shadow: var(--shadow-low);
}

.btn-small {
  min-height: 36px;
  padding: 8px 15px;
  font-size: 13px;
}

.btn-disabled,
.btn:disabled {
  cursor: not-allowed;
  opacity: .55;
  transform: none;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.reveal {
  transition: opacity .55s ease, transform .55s ease;
}

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

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

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

.topbar-inner {
  width: 100%;
  max-width: var(--wide-max);
  min-height: var(--header-height);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 22px;
}

.brand {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 9px;
  flex-shrink: 0;
}

.brand-logo {
  width: 28px;
  height: 28px;
  object-fit: contain;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 900;
  letter-spacing: -.02em;
}

.brand-local {
  color: var(--color-ink-muted);
  font-size: 12px;
  font-weight: 600;
}

.mainnav {
  display: flex;
  align-items: center;
  gap: 2px;
  margin-left: auto;
}

.nav-item {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  gap: 6px;
  padding: 7px 9px;
  border-radius: var(--radius-sm);
  color: var(--color-ink-muted);
  font-size: 12.5px;
  font-weight: 550;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.nav-item svg {
  width: 14px;
  height: 14px;
}

.nav-item:hover {
  background: var(--color-page);
  color: var(--color-ink);
}

.nav-item.is-active {
  color: var(--color-ink);
  font-weight: 750;
}

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

.language {
  position: relative;
}

.lang-trigger,
.menu-toggle {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 5px;
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-ink-muted);
  font-size: 13px;
}

.lang-trigger:hover,
.menu-toggle:hover {
  background: var(--color-page);
  color: var(--color-ink);
}

.lang-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 130;
  width: 168px;
  padding: 7px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-panel);
  box-shadow: var(--shadow-high);
}

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

.lang-menu a {
  display: flex;
  min-height: 40px;
  align-items: center;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  color: var(--color-ink-muted);
}

.lang-menu a:hover,
.lang-menu a[aria-current="true"] {
  background: var(--color-page);
  color: var(--color-ink);
}

.btn-login {
  min-height: 38px;
  padding: 8px 18px;
  font-size: 13.5px;
  font-weight: 650;
}

.menu-toggle {
  display: none;
}

.menu-toggle-lines {
  position: relative;
  width: 19px;
  height: 14px;
}

.menu-toggle-lines::before,
.menu-toggle-lines::after,
.menu-toggle-lines {
  border-top: 2px solid var(--color-ink);
}

.menu-toggle-lines::before,
.menu-toggle-lines::after {
  position: absolute;
  left: 0;
  width: 19px;
  content: "";
}

.menu-toggle-lines::before {
  top: 4px;
}

.menu-toggle-lines::after {
  top: 10px;
}

.mobile-nav {
  display: none;
}

.nav-veil {
  display: none;
}

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

.footer-inner {
  padding-top: 64px;
  padding-bottom: 28px;
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(220px, 1.3fr) repeat(3, minmax(150px, 1fr));
  gap: 40px;
}

.footer-brand {
  max-width: 360px;
}

.footer-brand .brand {
  margin-bottom: 15px;
}

.footer-brand .brand-local,
.footer-copy,
.footer-column a {
  color: var(--color-footer-muted);
}

.footer-copy {
  font-size: 14px;
}

.footer-column h2 {
  margin-bottom: 14px;
  color: var(--color-footer-text);
  font-size: 14px;
  letter-spacing: .02em;
}

.footer-links {
  display: grid;
  gap: 6px;
}

.footer-column a {
  display: inline-flex;
  min-height: 30px;
  align-items: center;
  font-size: 13px;
}

.footer-column a:hover {
  color: var(--color-footer-text);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 18px;
  margin-top: 44px;
  padding-top: 20px;
  border-top: 1px solid var(--color-ink-muted);
  color: var(--color-footer-muted);
  font-size: 12px;
}

.footer-legal a {
  min-height: 28px;
  display: inline-flex;
  align-items: center;
}

.prose {
  color: var(--color-ink);
  font-size: 16px;
  line-height: 1.85;
}

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

.prose h2 {
  margin-top: 64px;
  margin-bottom: 20px;
}

.prose h3 {
  margin-top: 36px;
  margin-bottom: 14px;
}

.prose a:not(.btn):not(.btn-primary):not(.btn-secondary) {
  color: var(--color-accent-strong);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.prose li + li {
  margin-top: 8px;
}

.prose img {
  border-radius: var(--radius-md);
}

body:has(.toc-tabs) section[id] {
  scroll-margin-top: 138px;
}

@media (max-width: 1180px) {
  .mainnav {
    display: none;
  }

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

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

  .nav-veil {
    position: fixed;
    inset: var(--header-height) 0 0;
    z-index: 105;
    background: var(--color-overlay);
  }

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

  .mobile-nav {
    position: absolute;
    top: 100%;
    right: 0;
    left: 0;
    z-index: 110;
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
    overscroll-behavior: contain;
    border-top: 1px solid var(--color-line);
    border-bottom: 1px solid var(--color-line);
    padding: 10px var(--gutter) 18px;
    background: var(--color-panel);
    box-shadow: var(--shadow-high);
  }

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

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

  .mobile-nav a:hover,
  .mobile-nav a.is-active {
    background: var(--color-page);
    color: var(--color-ink);
  }

  .mobile-nav svg {
    width: 16px;
    height: 16px;
  }

  .mobile-language {
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid var(--color-line);
  }
}

@media (max-width: 768px) {
  .no-break {
    white-space: normal;
  }

  h1 {
    font-size: clamp(28px, 10vw, 40px);
    line-height: 1.12;
  }

  h2 {
    font-size: clamp(28px, 8vw, 36px);
  }

  .section {
    padding-top: 64px;
    padding-bottom: 64px;
  }

  .topbar-inner {
    gap: 10px;
  }

  .brand-local,
  .lang-trigger-label {
    display: none;
  }

  .btn-login {
    padding-inline: 13px;
  }

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

@media (max-width: 640px) {
  .tilt,
  [class*="tilt-"] {
    transform: none;
  }

  .button-row,
  .button-row > * {
    width: 100%;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }

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

  .prose {
    font-size: 15px;
  }
}

@media (max-width: 390px) {
  .topbar-inner {
    padding-inline: 16px;
  }

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

  .brand-logo {
    width: 26px;
    height: 26px;
  }

  .header-tools {
    gap: 2px;
  }
}

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

  *,
  *::before,
  *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }

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