:root {
  --color-bg: #FFFFFF;
  --color-panel: #F7F7F8;
  --color-panel-strong: #F0F0F2;
  --color-border: #E6E6EA;
  --color-border-strong: #D8D8DE;
  --color-accent: #F2AE1C;
  --color-accent-dark: #C98D08;
  --color-text: #1B1C1F;
  --color-text-muted: #5F6168;
  --color-success: #2E9E6B;
  --color-warning: #E09112;
  --color-error: #D9463C;
  --color-mint: #D9F2E4;
  --color-sky: #DCEDFB;
  --color-lilac: #EAE3F9;
  --color-pink: #FBE2EA;
  --color-butter: #FBF0D6;
  --color-white: #FFFFFF;
  --color-flag-red: #E24438;
  --color-flag-blue: #33549E;
  --color-flag-green: #2F9E62;
  --color-focus-shadow: rgba(201, 141, 8, .18);
  --color-shadow-light: rgba(27, 28, 31, .04);
  --color-shadow-mid: rgba(27, 28, 31, .07);
  --color-shadow-deep: rgba(27, 28, 31, .09);
  --color-accent-wash: rgba(242, 174, 28, .20);
  --color-accent-fade: rgba(242, 174, 28, .09);
  --color-accent-clear: rgba(242, 174, 28, 0);
  --color-accent-border: rgba(201, 141, 8, .25);
  --color-ink-border: rgba(27, 28, 31, .07);
  --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', 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;
  --radius-xs: 6px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-pill: 999px;
  --shadow-soft: 0 1px 2px var(--color-shadow-light), 0 10px 28px var(--color-shadow-mid);
  --shadow-card: 0 1px 2px var(--color-shadow-light), 0 16px 36px var(--color-shadow-deep);
  --header-height: 72px;
  --gutter: clamp(16px, 3vw, 32px);
  --wrap: 1160px;
  --wrap-wide: 1320px;
  --content: 760px;
  --section-space: clamp(72px, 9vw, 120px);
  --toc-offset: 88px;
  --motion-fast: 150ms;
  --motion-normal: 360ms;
}

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

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

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  margin: 0;
  overflow-x: clip;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

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

img {
  height: auto;
}

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

button {
  border: 0;
  cursor: pointer;
}

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

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

ul,
ol {
  padding: 0;
}

ul {
  list-style: none;
}

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

code {
  overflow-wrap: anywhere;
}

pre {
  max-width: 100%;
  overflow-x: auto;
  padding: 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-panel);
  line-height: 1.65;
  -webkit-overflow-scrolling: touch;
}

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

:where(a, button, summary, input, select, textarea, [tabindex], [role="tab"]):focus-visible {
  outline: 2px solid var(--color-accent-dark);
  outline-offset: 3px;
  border-radius: var(--radius-xs);
  box-shadow: 0 0 0 5px var(--color-focus-shadow);
}

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

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

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

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

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

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

.section-soft {
  background: var(--color-panel);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 30px;
  padding: 4px 13px;
  border: 1px solid var(--color-accent-border);
  border-radius: var(--radius-pill);
  background: var(--color-butter);
  color: var(--color-accent-dark);
  font-size: 13px;
  font-weight: 750;
  letter-spacing: .02em;
}

.eyebrow::before,
.status-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--color-accent);
  content: "";
}

.display-title,
.hero-h1,
h1 {
  font-family: var(--font-display);
  font-size: clamp(52px, 5vw, 72px);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -.02em;
  text-wrap: balance;
}

.section-title,
h2 {
  font-family: var(--font-display);
  font-size: clamp(32px, 4vw, 48px);
  font-weight: 850;
  line-height: 1.18;
  letter-spacing: -.018em;
  text-wrap: balance;
}

h3 {
  font-size: clamp(20px, 2vw, 26px);
  font-weight: 800;
  line-height: 1.3;
}

.lead {
  max-width: 720px;
  color: var(--color-text-muted);
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.8;
}

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

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

.marker {
  position: relative;
  z-index: 0;
  display: inline-block;
}

.marker::after {
  position: absolute;
  z-index: -1;
  right: -3%;
  bottom: .06em;
  left: -3%;
  height: .17em;
  border-radius: .09em;
  background: var(--color-accent);
  content: "";
  transform: rotate(-1.1deg);
}

.card,
.panel {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg);
  box-shadow: var(--shadow-soft);
}

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

.btn {
  display: inline-flex;
  min-width: 24px;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 0 26px;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  font-weight: 750;
  line-height: 1.2;
  text-align: center;
  transition: transform var(--motion-fast), box-shadow var(--motion-fast), border-color var(--motion-fast), background var(--motion-fast);
}

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

.btn-primary {
  background: var(--color-text);
  color: var(--color-bg);
  box-shadow: var(--shadow-soft);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}

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

.btn-secondary:hover {
  border-color: var(--color-text);
  transform: translateY(-2px);
}

.btn-accent {
  background: var(--color-accent);
  color: var(--color-text);
}

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

.btn[aria-disabled="true"],
.btn:disabled {
  cursor: not-allowed;
  opacity: .55;
  transform: none;
}

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

.head-inner {
  display: flex;
  width: 100%;
  max-width: var(--wrap-wide);
  height: var(--header-height);
  align-items: center;
  gap: 32px;
  margin: 0 auto;
  padding-inline: var(--gutter);
}

.brand {
  display: inline-flex;
  min-height: 44px;
  flex: 0 0 auto;
  align-items: center;
  gap: 10px;
  font-size: 19px;
  font-weight: 850;
  letter-spacing: -.01em;
}

.brand img,
.footer-brand img {
  width: 32px;
  height: 32px;
}

.brand-local {
  color: var(--color-text-muted);
  font-size: 15px;
  font-weight: 600;
}

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

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
  color: var(--color-text-muted);
  font-size: 15px;
  font-weight: 600;
}

.nav-links > li > a,
.more-toggle {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 5px;
  padding-inline: 2px;
}

.nav-links a:hover,
.more-toggle:hover,
.nav-links a[aria-current="page"] {
  color: var(--color-text);
}

.nav-links a[aria-current="page"] {
  box-shadow: inset 0 -3px var(--color-accent);
}

.more-nav {
  position: relative;
}

.more-menu {
  position: absolute;
  top: calc(100% + 8px);
  left: 50%;
  min-width: 184px;
  padding: 8px;
  visibility: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg);
  box-shadow: var(--shadow-card);
  opacity: 0;
  transform: translate(-50%, 4px);
  transition: opacity var(--motion-fast), transform var(--motion-fast), visibility var(--motion-fast);
}

.more-nav:hover .more-menu,
.more-nav:focus-within .more-menu {
  visibility: visible;
  opacity: 1;
  transform: translate(-50%, 0);
}

.more-menu a {
  display: flex;
  min-height: 42px;
  align-items: center;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  color: var(--color-text);
}

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

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

.language-menu {
  position: relative;
}

.language-toggle,
.menu-toggle {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 5px;
  padding: 6px 9px;
  background: transparent;
  color: var(--color-text-muted);
}

.language-popover {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 4;
  min-width: 158px;
  padding: 8px;
  visibility: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg);
  box-shadow: var(--shadow-card);
  opacity: 0;
  transform: translateY(4px);
  transition: opacity var(--motion-fast), transform var(--motion-fast), visibility var(--motion-fast);
}

.language-menu.is-open .language-popover {
  visibility: visible;
  opacity: 1;
  transform: translateY(0);
}

.language-popover a {
  display: flex;
  min-height: 42px;
  align-items: center;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
}

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

.login-link {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  justify-content: center;
  padding-inline: 20px;
  border-radius: 10px;
  background: var(--color-text);
  color: var(--color-bg);
  font-size: 14px;
  font-weight: 700;
}

.menu-toggle {
  display: none;
}

.menu-toggle svg {
  width: 22px;
  height: 22px;
}

.mobile-drawer {
  display: none;
}

.nav-veil {
  display: none;
}

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

.footer-main {
  display: grid;
  grid-template-columns: minmax(220px, 1.35fr) repeat(3, minmax(150px, 1fr));
  gap: 48px;
  padding-top: 64px;
  padding-bottom: 52px;
}

.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 19px;
  font-weight: 850;
}

.footer-copy {
  max-width: 330px;
  margin-top: 16px;
  color: var(--color-text-muted);
}

.footer-title {
  margin-bottom: 14px;
  font-size: 14px;
  font-weight: 800;
}

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

.footer-links a {
  display: inline-flex;
  min-height: 32px;
  align-items: center;
  color: var(--color-text-muted);
  font-size: 14px;
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding-top: 22px;
  padding-bottom: 24px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 13px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
}

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

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

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

.prose {
  overflow-wrap: break-word;
}

.prose > * + * {
  margin-top: 1.25em;
}

.prose h2 {
  margin-top: 2.1em;
}

.prose h3 {
  margin-top: 1.7em;
}

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

.prose ul,
.prose ol {
  padding-left: 1.3em;
}

.prose ul {
  list-style: disc;
}

.prose li + li {
  margin-top: .45em;
}

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

@media (max-width: 980px) {
  .desktop-nav {
    display: none;
  }

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

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

  .nav-veil {
    position: fixed;
    z-index: 98;
    inset: var(--header-height) 0 0;
    display: block;
    visibility: hidden;
    background: var(--color-shadow-mid);
    opacity: 0;
    transition: opacity var(--motion-fast), visibility var(--motion-fast);
  }

  .nav-veil.is-open {
    visibility: visible;
    opacity: 1;
  }

  .mobile-drawer {
    position: fixed;
    z-index: 101;
    top: var(--header-height);
    right: 0;
    left: 0;
    display: block;
    max-height: calc(100dvh - var(--header-height));
    padding: 12px var(--gutter) 24px;
    visibility: hidden;
    overflow-y: auto;
    overscroll-behavior: contain;
    border-bottom: 1px solid var(--color-border);
    background: var(--color-bg);
    box-shadow: var(--shadow-card);
    opacity: 0;
    transform: translateY(-8px);
    transition: opacity var(--motion-fast), transform var(--motion-fast), visibility var(--motion-fast);
  }

  .mobile-drawer.is-open {
    visibility: visible;
    opacity: 1;
    transform: translateY(0);
  }

  .mobile-drawer ul {
    display: grid;
  }

  .mobile-drawer a {
    display: flex;
    width: 100%;
    min-height: 48px;
    align-items: center;
    justify-content: space-between;
    padding: 10px 12px;
    border-radius: var(--radius-sm);
    font-weight: 650;
  }

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

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

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

@media (max-width: 768px) {
  .display-title,
  .hero-h1,
  h1 {
    font-size: clamp(32px, 10vw, 40px);
    line-height: 1.13;
  }

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

  .language-toggle .language-name {
    display: none;
  }

  .section {
    padding-top: 72px;
    padding-bottom: 72px;
  }
}

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

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

  .head-inner {
    gap: 8px;
  }

  .brand-local {
    display: none;
  }

  .login-link {
    min-width: 56px;
    padding-inline: 13px;
  }

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

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

  .btn {
    padding-inline: 21px;
  }
}

@media (max-width: 380px) {
  .brand span:first-of-type {
    font-size: 17px;
  }

  .language-toggle {
    display: none;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation: none !important;
    transition: none !important;
  }

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