:root {
  --color-canvas: #FFFFFF;
  --color-panel: #F6F6F9;
  --color-panel-strong: #EEEEF4;
  --color-line: #E3E3EB;
  --color-accent: #F0328C;
  --color-accent-deep: #C21B6E;
  --color-coral: #FF7A59;
  --color-ink: #101014;
  --color-ink-muted: #5A5A66;
  --color-success: #17A560;
  --color-warning: #E9A400;
  --color-error: #DE3B3B;
  --color-sky: #2F9BE8;
  --color-night: #0E0E11;
  --color-white: #FFFFFF;
  --color-flag-red: #D0342C;
  --color-flag-blue: #27427C;
  --color-flag-gold: #F5C400;
  --color-flag-black: #22222A;
  --color-night-text: rgba(255, 255, 255, 0.74);
  --color-night-line: rgba(255, 255, 255, 0.18);
  --color-night-dot: rgba(255, 255, 255, 0.07);
  --color-focus-halo: rgba(240, 50, 140, 0.2);
  --color-shadow-soft: rgba(16, 16, 20, 0.05);
  --color-shadow-mid: rgba(16, 16, 20, 0.07);
  --color-shadow-deep: rgba(16, 16, 20, 0.1);
  --color-accent-shadow: rgba(240, 50, 140, 0.24);
  --font-display: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;
  --radius-xs: 8px;
  --radius-sm: 12px;
  --radius-card: 16px;
  --radius-large: 28px;
  --radius-pill: 999px;
  --shadow-lift: 0 1px 2px var(--color-shadow-soft), 0 6px 18px var(--color-shadow-mid), 0 18px 44px var(--color-shadow-soft);
  --shadow-card: 0 1px 2px var(--color-shadow-soft), 0 14px 34px var(--color-shadow-mid);
  --shadow-cta: 0 2px 6px var(--color-accent-shadow), 0 10px 26px var(--color-accent-shadow);
  --header-height: 72px;
  --content-max: 1200px;
  --content-wide: 1380px;
  --gutter: clamp(16px, 4vw, 40px);
  --section-space: clamp(72px, 9vw, 128px);
  --toc-offset: 88px;
  --transition-fast: 150ms ease;
  --transition-base: 280ms cubic-bezier(0.2, 0.7, 0.2, 1);
}

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

html {
  margin: 0;
  padding: 0;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  margin: 0;
  padding: 0;
  overflow-x: clip;
  background: var(--color-canvas);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

main,
section,
article,
aside,
header,
footer,
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;
}

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

h1,
h2,
h3 {
  display: block;
}

h1 {
  margin: 0 0 24px;
  font-size: clamp(52px, 5vw, 72px);
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

h2 {
  margin: 0 0 24px;
  font-size: clamp(36px, 4vw, 54px);
  font-weight: 850;
  letter-spacing: -0.018em;
  line-height: 1.14;
}

h3 {
  margin: 0 0 14px;
  font-size: clamp(22px, 2.2vw, 30px);
  font-weight: 800;
  line-height: 1.25;
}

h4 {
  margin: 0 0 10px;
  font-size: 18px;
  font-weight: 800;
}

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-card);
  background: var(--color-night);
  color: var(--color-white);
  -webkit-overflow-scrolling: touch;
}

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

table {
  border-collapse: collapse;
}

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

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

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

.gradient-text {
  background: linear-gradient(96deg, var(--color-accent) 12%, var(--color-coral) 92%);
  background-clip: text;
  color: transparent;
  -webkit-background-clip: text;
}

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

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

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

.section-compact {
  padding-top: clamp(48px, 6vw, 80px);
  padding-bottom: clamp(48px, 6vw, 80px);
  overflow-x: clip;
}

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

.section-night {
  background-color: var(--color-night);
  background-image: radial-gradient(var(--color-night-dot) 1px, transparent 1.4px);
  background-size: 18px 18px;
  color: var(--color-night-text);
}

.section-night h1,
.section-night h2,
.section-night h3,
.section-night h4 {
  color: var(--color-white);
}

.eyebrow {
  display: inline-flex;
  max-width: 100%;
  align-items: center;
  gap: 8px;
  margin: 0 0 20px;
  padding: 7px 15px;
  overflow: hidden;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-ink-muted);
  font-size: 13px;
  font-weight: 700;
}

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

.status-dot.is-success {
  background: var(--color-success);
}

.status-dot.is-warning {
  background: var(--color-warning);
}

.status-dot.is-sky {
  background: var(--color-sky);
}

.lead {
  max-width: 720px;
  color: var(--color-ink-muted);
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.6;
}

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

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

.button,
.btn-primary,
.btn-secondary,
.btn-dark,
.btn-quiet {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 12px 28px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-weight: 800;
  line-height: 1.2;
  text-align: center;
  transition: transform var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast), color var(--transition-fast);
}

.btn-primary {
  background: linear-gradient(120deg, var(--color-accent) 20%, var(--color-coral) 110%);
  box-shadow: var(--shadow-cta);
  color: var(--color-white);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 10px var(--color-accent-shadow), 0 16px 34px var(--color-accent-shadow);
}

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

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

.btn-dark {
  background: var(--color-ink);
  color: var(--color-white);
}

.btn-dark:hover {
  transform: translateY(-1px);
  background: var(--color-accent-deep);
}

.btn-quiet {
  border-color: var(--color-line);
  background: var(--color-panel);
  color: var(--color-ink);
}

.btn-quiet:hover {
  border-color: var(--color-accent);
  color: var(--color-accent-deep);
}

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

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

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

.card {
  padding: clamp(22px, 3vw, 32px);
  box-shadow: var(--shadow-card);
}

.panel {
  padding: clamp(20px, 3vw, 28px);
  background: var(--color-panel);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

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

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

.reveal {
  transition: opacity 620ms ease, transform 620ms cubic-bezier(0.2, 0.7, 0.2, 1);
}

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

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

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

.header-shell {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 26px;
  padding-inline: var(--gutter);
}

.brand-link {
  min-height: 44px;
  display: inline-flex;
  flex-shrink: 0;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
}

.brand-logo {
  width: 28px;
  height: 28px;
  display: block;
}

.brand-main {
  font-size: 19px;
  font-weight: 900;
  letter-spacing: 0.01em;
}

.brand-local {
  color: var(--color-ink-muted);
  font-size: 14px;
  font-weight: 650;
}

.desktop-nav {
  margin-left: auto;
  display: flex;
  align-items: center;
  color: var(--color-ink-muted);
  font-size: 14px;
  font-weight: 650;
}

.desktop-nav a {
  min-height: 32px;
  position: relative;
  display: inline-flex;
  align-items: center;
}

.desktop-nav a + a::before {
  content: "·";
  margin-inline: 12px;
  color: var(--color-line);
  font-weight: 800;
}

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

.desktop-nav a.is-active::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--color-accent);
  transform: translateX(-50%);
}

.desktop-nav a.is-active:not(:first-child)::after {
  left: calc(50% + 12px);
}

.header-tools {
  display: flex;
  flex-shrink: 0;
  align-items: center;
  gap: 12px;
}

.language-control {
  position: relative;
}

.language-button {
  min-width: 44px;
  min-height: 44px;
  padding: 8px;
  border: 0;
  background: transparent;
  color: var(--color-ink-muted);
  font-size: 13px;
  font-weight: 700;
}

.language-menu {
  width: 168px;
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 120;
  display: none;
  padding: 8px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  background: var(--color-canvas);
  box-shadow: var(--shadow-lift);
}

.language-control.is-open .language-menu {
  display: grid;
}

.language-menu a {
  min-height: 44px;
  display: flex;
  align-items: center;
  padding-inline: 12px;
  border-radius: var(--radius-xs);
  font-size: 14px;
  font-weight: 650;
}

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

.header-login {
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 21px;
  border-radius: var(--radius-pill);
  background: var(--color-ink);
  color: var(--color-white);
  font-size: 14px;
  font-weight: 800;
  transition: transform var(--transition-fast), background var(--transition-fast);
}

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

.menu-toggle {
  min-width: 44px;
  min-height: 44px;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 0;
  border: 1px solid var(--color-line);
  border-radius: 50%;
  background: var(--color-canvas);
}

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

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

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

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

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

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

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::before {
  transform: translateY(6px) rotate(45deg);
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::after {
  transform: translateY(-6px) rotate(-45deg);
}

.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: 12px var(--gutter) calc(24px + env(safe-area-inset-bottom, 0px));
  border-bottom: 1px solid var(--color-line);
  background: var(--color-canvas);
  box-shadow: var(--shadow-lift);
  overscroll-behavior: contain;
}

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

.mobile-nav a {
  width: 100%;
  min-height: 48px;
  display: flex;
  align-items: center;
  padding: 11px 12px;
  border-bottom: 1px solid var(--color-line);
  font-weight: 750;
}

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

.mobile-language-group {
  display: grid;
  margin-top: 12px;
}

.mobile-language-group strong {
  padding: 10px 12px 4px;
  color: var(--color-ink-muted);
  font-size: 12px;
  letter-spacing: 0.08em;
}

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

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

.site-footer {
  overflow-x: clip;
  border-top: 1px solid var(--color-night-line);
  background-color: var(--color-night);
  background-image: radial-gradient(var(--color-night-dot) 1px, transparent 1.4px);
  background-size: 18px 18px;
  color: var(--color-night-text);
}

.footer-shell {
  padding-top: 72px;
  padding-bottom: 28px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1fr 0.8fr;
  gap: 42px;
}

.footer-brand {
  max-width: 320px;
}

.footer-brandline {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  margin-bottom: 18px;
  color: var(--color-white);
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 900;
}

.footer-logo {
  width: 31px;
  height: 31px;
}

.footer-title {
  margin: 0 0 16px;
  color: var(--color-white);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.08em;
}

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

.footer-links a {
  min-height: 32px;
  display: inline-flex;
  align-items: center;
  width: fit-content;
  max-width: 100%;
}

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

.footer-trust {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 22px;
}

.footer-chip {
  max-width: 100%;
  padding: 5px 10px;
  overflow: hidden;
  border: 1px solid var(--color-night-line);
  border-radius: var(--radius-pill);
  color: var(--color-white);
  font-size: 12px;
  font-weight: 700;
}

.footer-bottom {
  margin-top: 52px;
  padding-top: 24px;
  border-top: 1px solid var(--color-night-line);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 14px 28px;
  font-size: 13px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 22px;
}

.footer-legal a {
  min-height: 24px;
}

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

@media (max-width: 1120px) {
  .desktop-nav {
    display: none;
  }

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

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

  .language-control {
    display: none;
  }

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

@media (max-width: 768px) {
  :root {
    --header-height: 68px;
    --toc-offset: 82px;
  }

  h1 {
    font-size: clamp(32px, 9.5vw, 40px);
    line-height: 1.12;
  }

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

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

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

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

  .button-row > .button,
  .button-row > .btn-primary,
  .button-row > .btn-secondary,
  .button-row > .btn-dark,
  .button-row > .btn-quiet {
    flex: 1 1 180px;
  }

  .brand-local {
    display: none;
  }
}

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

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 34px;
  }

  .footer-bottom {
    display: grid;
  }
}

@media (max-width: 420px) {
  .header-shell {
    gap: 8px;
  }

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

  .header-login {
    min-width: 60px;
    padding-inline: 14px;
  }

  .menu-toggle {
    min-width: 42px;
    min-height: 42px;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-duration: 0s;
    transition-duration: 0s;
  }

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