:root {
  --color-canvas: #FFFFFF;
  --color-panel: #F7F8FA;
  --color-panel-strong: #EFF1F5;
  --color-line: #E3E6EB;
  --color-primary: #0D5EF4;
  --color-primary-deep: #0A46C4;
  --color-secondary: #7A3BFF;
  --color-ink: #12161F;
  --color-muted: #5A6372;
  --color-positive: #12A150;
  --color-warning: #E8930C;
  --color-negative: #DE3B3B;
  --color-white-soft: #FFFFFF;
  --color-focus-halo: rgba(13, 94, 244, 0.22);
  --color-primary-shadow: rgba(13, 94, 244, 0.42);
  --color-ink-shadow-soft: rgba(18, 22, 31, 0.05);
  --color-ink-shadow-mid: rgba(18, 22, 31, 0.12);
  --color-ink-shadow-deep: rgba(18, 22, 31, 0.20);
  --color-secondary-soft: rgba(122, 59, 255, 0.10);
  --color-primary-soft: rgba(13, 94, 244, 0.08);
  --color-positive-soft: rgba(18, 161, 80, 0.10);

  --flag-red: #CE2F3B;
  --flag-navy: #28376F;
  --flag-white: #FFFFFF;
  --flag-gold: #F3C63F;
  --flag-black: #26262B;

  --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, 'Courier New', monospace;

  --radius-2xs: 6px;
  --radius-xs: 8px;
  --radius-sm: 12px;
  --radius-md: 16px;
  --radius-lg: 22px;
  --radius-xl: 30px;
  --radius-pill: 999px;

  --shadow-card: 0 1px 2px var(--color-ink-shadow-soft), 0 10px 28px -12px var(--color-ink-shadow-mid);
  --shadow-window: 0 2px 6px var(--color-ink-shadow-soft), 0 28px 60px -24px var(--color-ink-shadow-deep), 0 70px 130px -60px var(--color-focus-halo);
  --shadow-chip: 0 1px 2px var(--color-ink-shadow-soft), 0 8px 22px -10px var(--color-ink-shadow-deep);
  --shadow-primary: 0 10px 26px -8px var(--color-primary-shadow);

  --content-wide: 1320px;
  --content-main: 1160px;
  --content-reading: 820px;
  --header-height: 64px;
  --gutter: clamp(16px, 3vw, 28px);
  --section-space: clamp(72px, 9vw, 128px);
  --toc-offset: 82px;
  --ease-standard: cubic-bezier(0.22, 1, 0.36, 1);
}

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

html {
  background: var(--color-canvas);
  color: var(--color-ink);
  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-canvas);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

img,
picture,
video,
canvas {
  display: block;
  max-width: 100%;
  height: auto;
}

svg {
  flex-shrink: 0;
}

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

button,
summary,
select {
  cursor: pointer;
}

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

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

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

ul,
ol {
  padding-left: 1.35em;
}

nav ul,
.site-footer ul,
.platform-list,
.flag-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

h1,
h2,
h3,
h4 {
  color: var(--color-ink);
  font-family: var(--font-display);
  font-weight: 800;
  text-wrap: balance;
}

h1,
h2,
h3 {
  display: block;
}

h1 {
  margin-bottom: 22px;
  font-size: clamp(52px, 5.3vw, 72px);
  line-height: 1.12;
  letter-spacing: -0.012em;
}

h2 {
  margin-bottom: 20px;
  font-size: clamp(34px, 4vw, 50px);
  line-height: 1.16;
  letter-spacing: -0.01em;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(22px, 2.5vw, 30px);
  line-height: 1.25;
}

h4 {
  margin-bottom: 8px;
  font-size: 18px;
  line-height: 1.35;
}

strong {
  font-weight: 700;
}

small {
  font-size: 0.875em;
}

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

code {
  overflow-wrap: anywhere;
  border-radius: var(--radius-2xs);
  background: var(--color-panel-strong);
  padding: 0.14em 0.38em;
  font-size: 0.9em;
}

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

pre code {
  overflow-wrap: normal;
  background: transparent;
  padding: 0;
}

hr {
  border: 0;
  border-top: 1px solid var(--color-line);
}

::selection {
  background: var(--color-focus-halo);
  color: var(--color-ink);
}

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

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

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

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

.section {
  position: relative;
  overflow-x: clip;
  padding-top: var(--section-space);
  padding-bottom: var(--section-space);
}

.section-compact {
  padding-top: clamp(46px, 6vw, 76px);
  padding-bottom: clamp(46px, 6vw, 76px);
}

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

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  min-height: 28px;
  margin-bottom: 18px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  padding: 3px 14px;
  color: var(--color-muted);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
}

.eyebrow-dot,
.status-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: var(--radius-pill);
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
}

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

.gradient-text {
  background: linear-gradient(92deg, var(--color-primary) 8%, var(--color-secondary) 92%);
  color: transparent;
  background-clip: text;
  -webkit-background-clip: text;
}

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

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

.lead {
  max-width: 760px;
  color: var(--color-muted);
  font-size: clamp(17px, 2vw, 21px);
  line-height: 1.65;
}

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

.actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px;
}

.actions-centered {
  justify-content: center;
}

.button {
  display: inline-flex;
  min-width: 24px;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  gap: 9px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  padding: 10px 25px;
  font-weight: 700;
  line-height: 1.2;
  text-align: center;
  transition: transform 160ms var(--ease-standard), background-color 160ms ease, border-color 160ms ease, color 160ms ease, box-shadow 160ms ease;
}

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

.button-primary {
  background: var(--color-primary);
  color: var(--color-white-soft);
  box-shadow: var(--shadow-primary);
}

.button-primary:hover {
  background: var(--color-primary-deep);
}

.button-secondary {
  border-color: var(--color-line);
  background: var(--color-canvas);
  color: var(--color-ink);
}

.button-secondary:hover {
  border-color: var(--color-muted);
  background: var(--color-panel);
}

.button-quiet {
  border-color: var(--color-line);
  background: var(--color-panel);
  color: var(--color-primary);
  box-shadow: none;
}

.button-small {
  min-height: 38px;
  padding: 7px 17px;
  font-size: 14px;
}

.button[aria-disabled="true"],
.button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
  transform: none;
  box-shadow: none;
}

.panel,
.card {
  border: 1px solid var(--color-line);
  border-radius: var(--radius-lg);
  background: var(--color-canvas);
  box-shadow: var(--shadow-card);
}

.panel {
  padding: clamp(22px, 4vw, 38px);
}

.card {
  padding: 24px;
}

.reveal {
  transition: opacity 650ms var(--ease-standard), transform 650ms var(--ease-standard);
}

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

.reveal.shown {
  opacity: 1;
  transform: translateY(0);
}

.site-head {
  position: relative;
  z-index: 50;
  height: var(--header-height);
  border-bottom: 1px solid var(--color-line);
  background: var(--color-canvas);
}

.head-inner {
  display: flex;
  width: 100%;
  max-width: var(--content-wide);
  height: 100%;
  align-items: center;
  gap: 30px;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.site-brand img {
  width: 27px;
  height: 27px;
}

.brand-word {
  color: var(--color-ink);
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  letter-spacing: 0.01em;
}

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

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

.desktop-nav a {
  display: inline-flex;
  min-height: 36px;
  align-items: center;
  padding: 6px 2px;
  color: var(--color-muted);
  font-size: 14px;
  transition: color 150ms ease;
}

.desktop-nav a:hover,
.desktop-nav a.is-active,
.desktop-nav a[aria-current="page"] {
  color: var(--color-ink);
}

.desktop-nav a.is-active,
.desktop-nav a[aria-current="page"] {
  font-weight: 700;
}

.nav-separator {
  margin-inline: 10px;
  color: var(--color-line);
  font-weight: 800;
  user-select: none;
}

.head-tools {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 0 0 auto;
}

.language-menu {
  position: relative;
}

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

.language-trigger {
  gap: 6px;
  padding-inline: 8px;
  font-size: 13px;
}

.language-popover {
  position: absolute;
  top: calc(100% + 9px);
  right: 0;
  z-index: 55;
  width: 172px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-canvas);
  padding: 7px;
  box-shadow: var(--shadow-window);
}

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

.language-popover a {
  display: flex;
  min-height: 42px;
  align-items: center;
  border-radius: var(--radius-xs);
  padding: 8px 11px;
  color: var(--color-muted);
  font-size: 14px;
}

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

.login-button {
  display: inline-flex;
  min-height: 36px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-pill);
  background: var(--color-primary);
  padding: 7px 20px;
  color: var(--color-white-soft);
  font-size: 13.5px;
  font-weight: 700;
  transition: background-color 150ms ease, transform 150ms ease;
}

.login-button:hover {
  background: var(--color-primary-deep);
  transform: translateY(-1px);
}

.menu-toggle {
  display: none;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-sm);
}

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: var(--radius-pill);
  background: var(--color-ink);
  content: "";
  transition: transform 160ms ease;
}

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

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

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

.menu-toggle[aria-expanded="true"] .menu-toggle-lines {
  background: transparent;
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::before {
  top: 0;
  transform: rotate(45deg);
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::after {
  top: 0;
  transform: rotate(-45deg);
}

.mobile-nav {
  display: none;
}

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

.nav-veil {
  display: none;
}

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

.footer-main {
  display: grid;
  grid-template-columns: minmax(250px, 1.35fr) repeat(3, minmax(150px, 1fr));
  gap: clamp(30px, 5vw, 68px);
  max-width: var(--content-wide);
  margin-inline: auto;
  padding: 68px var(--gutter) 42px;
}

.footer-brand {
  max-width: 350px;
}

.footer-brand .site-brand {
  margin-bottom: 14px;
}

.footer-brand p {
  color: var(--color-muted);
  font-size: 14px;
  line-height: 1.75;
}

.footer-column h2 {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.footer-column a {
  display: inline-flex;
  min-height: 30px;
  align-items: center;
  color: var(--color-muted);
  font-size: 14px;
}

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

.footer-column li + li {
  margin-top: 5px;
}

.footer-bottom {
  display: flex;
  max-width: var(--content-wide);
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-inline: auto;
  border-top: 1px solid var(--color-line);
  padding: 22px var(--gutter) 28px;
  color: var(--color-muted);
  font-size: 13px;
}

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

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

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

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

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

.prose a:not(.button) {
  color: var(--color-primary);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.prose blockquote {
  margin-inline: 0;
}

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

@media (max-width: 1120px) {
  .desktop-nav {
    gap: 0;
  }

  .desktop-nav a {
    font-size: 13px;
  }

  .nav-separator {
    margin-inline: 6px;
  }

  .brand-local {
    display: none;
  }
}

@media (max-width: 900px) {
  .desktop-nav,
  .language-menu {
    display: none;
  }

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

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

  .site-head {
    position: relative;
  }

  .mobile-nav {
    position: absolute;
    top: var(--header-height);
    right: 0;
    left: 0;
    z-index: 54;
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
    overscroll-behavior: contain;
    border-bottom: 1px solid var(--color-line);
    background: var(--color-canvas);
    padding: 10px var(--gutter) 18px;
    box-shadow: var(--shadow-window);
    -webkit-overflow-scrolling: touch;
  }

  .mobile-nav a {
    display: flex;
    width: 100%;
    min-height: 46px;
    align-items: center;
    border-bottom: 1px solid var(--color-line);
    padding: 10px 7px;
    color: var(--color-muted);
    font-weight: 600;
  }

  .mobile-nav a.is-active {
    color: var(--color-primary);
  }

  .mobile-language-list {
    margin-top: 12px;
  }

  .mobile-language-list strong {
    display: block;
    padding: 8px 7px 4px;
    font-family: var(--font-mono);
    font-size: 11px;
    letter-spacing: 0.07em;
  }

  .nav-veil {
    position: fixed;
    inset: var(--header-height) 0 0;
    z-index: 45;
    border: 0;
    background: var(--color-ink-shadow-mid);
  }

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

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

@media (max-width: 768px) {
  h1 {
    font-size: clamp(32px, 9.5vw, 40px);
    line-height: 1.13;
    letter-spacing: -0.01em;
  }

  h2 {
    font-size: clamp(28px, 7.5vw, 36px);
  }

  .lead {
    font-size: 17px;
  }

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

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

@media (max-width: 640px) {
  .no-break {
    white-space: normal;
  }

  :root {
    --gutter: 16px;
  }

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

  .actions,
  .actions-centered {
    align-items: stretch;
    flex-direction: column;
  }

  .button {
    width: 100%;
  }

  .login-button {
    min-height: 38px;
    padding-inline: 16px;
  }

  .brand-word {
    font-size: 18px;
  }

  .footer-main {
    grid-template-columns: 1fr;
    padding-top: 52px;
  }
}

@media (max-width: 380px) {
  .head-inner {
    gap: 8px;
  }

  .site-brand {
    gap: 6px;
  }

  .site-brand img {
    width: 24px;
    height: 24px;
  }

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

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation: none !important;
    transition-duration: 0.01ms !important;
  }

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