:root {
  --color-canvas: #FFFFFF;
  --color-panel: #F7F8FB;
  --color-panel-strong: #EFF1F7;
  --color-line: #E4E7F0;
  --color-accent: #4B4DE1;
  --color-accent-deep: #3835B8;
  --color-accent-soft: #9FA0F4;
  --color-accent-wash: #EDEEFC;
  --color-ink: #171A2E;
  --color-ink-muted: #5C6175;
  --color-success: #1B9E62;
  --color-success-line: #BCE3CF;
  --color-success-wash: #F1FAF5;
  --color-warning: #C07C14;
  --color-error: #D6453D;
  --color-white: #FFFFFF;
  --color-overlay: rgba(23, 26, 46, 0.32);
  --color-shadow-soft: rgba(23, 26, 46, 0.06);
  --color-shadow-mid: rgba(23, 26, 46, 0.09);
  --color-shadow-accent: rgba(75, 77, 225, 0.14);
  --color-shadow-button: rgba(56, 53, 184, 0.22);
  --color-shadow-button-deep: rgba(75, 77, 225, 0.26);
  --color-focus-wash: rgba(75, 77, 225, 0.18);
  --color-flag-red: #D8402F;
  --color-flag-navy: #232E63;
  --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, 'Noto Sans SC', monospace;
  --radius-small: 10px;
  --radius-medium: 16px;
  --radius-large: 22px;
  --radius-xlarge: 30px;
  --radius-pill: 999px;
  --shadow-soft: 0 1px 2px var(--color-shadow-soft), 0 8px 22px var(--color-shadow-soft);
  --shadow-focus: 0 1px 2px var(--color-shadow-soft), 0 14px 34px var(--color-shadow-accent), 0 34px 70px var(--color-shadow-mid);
  --shadow-button: 0 2px 6px var(--color-shadow-button), 0 10px 24px var(--color-shadow-button-deep);
  --page-width: 1240px;
  --reading-width: 780px;
  --header-height: 66px;
  --gutter: 36px;
  --section-space: 104px;
  --focus-ring: 0 0 0 4px var(--color-focus-wash);
  --transition-fast: 150ms ease;
  --transition-normal: 260ms ease;
  --toc-offset: 86px;
}

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

html {
  background: var(--color-canvas);
  color: var(--color-ink);
  font-family: var(--font-body);
  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;
  background: var(--color-canvas);
  color: var(--color-ink);
  font-family: var(--font-body);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: clip;
}

main,
section,
article,
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;
}

a {
  color: var(--color-accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

a:hover {
  color: var(--color-accent-deep);
}

a,
button,
summary,
[role="tab"],
select,
input,
textarea {
  transition: color var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast), transform var(--transition-fast);
}

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

p,
ul,
ol,
blockquote,
pre,
table {
  margin-top: 0;
  margin-bottom: 1.25em;
}

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

li::marker {
  color: var(--color-accent);
}

h1,
h2,
h3,
h4 {
  margin-top: 0;
  color: var(--color-ink);
  font-family: var(--font-display);
  font-weight: 800;
  text-wrap: balance;
}

h1 {
  max-width: 100%;
  margin-bottom: 24px;
  font-size: clamp(52px, 5.15vw, 64px);
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  margin-bottom: 20px;
  font-size: clamp(34px, 4vw, 50px);
  line-height: 1.16;
  letter-spacing: -0.018em;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2vw, 27px);
  line-height: 1.3;
  letter-spacing: -0.01em;
}

h4 {
  margin-bottom: 8px;
  font-size: 18px;
  line-height: 1.4;
}

strong {
  color: var(--color-ink);
  font-weight: 700;
}

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

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

code {
  max-width: 100%;
  padding: 0.12em 0.35em;
  border-radius: var(--radius-small);
  background: var(--color-panel-strong);
  overflow-wrap: anywhere;
}

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

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

hr {
  height: 1px;
  margin: 40px 0;
  border: 0;
  background: var(--color-line);
}

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

.gradient-text,
.grad {
  background: linear-gradient(94deg, var(--color-accent-deep) 0%, var(--color-accent) 46%, var(--color-accent-soft) 100%);
  color: transparent;
  background-clip: text;
  -webkit-background-clip: text;
}

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

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

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

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

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

.section-heading {
  max-width: 760px;
  margin-bottom: 52px;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  margin-bottom: 14px;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.lead {
  max-width: 760px;
  color: var(--color-ink-muted);
  font-size: clamp(18px, 2vw, 21px);
  line-height: 1.75;
}

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

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

.surface {
  border: 1px solid var(--color-line);
  border-radius: var(--radius-large);
  background: var(--color-canvas);
  box-shadow: var(--shadow-soft);
}

.panel {
  padding: 28px;
  border-radius: var(--radius-large);
  background: var(--color-panel);
}

.badge,
.status-badge,
.hero-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  max-width: 100%;
  min-height: 30px;
  padding: 4px 13px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-canvas);
  color: var(--color-ink-muted);
  font-size: 12px;
  font-weight: 650;
  line-height: 1.35;
  overflow: hidden;
}

.badge-dot,
.hero-chip-dot {
  width: 6px;
  height: 6px;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
  flex: 0 0 auto;
}

.badge-accent {
  border-color: var(--color-accent-soft);
  background: var(--color-accent-wash);
  color: var(--color-accent-deep);
}

.badge-success {
  border-color: var(--color-success-line);
  background: var(--color-success-wash);
  color: var(--color-success);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  min-width: 24px;
  min-height: 46px;
  padding: 0 25px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  cursor: pointer;
  font-size: 14.5px;
  font-weight: 700;
  line-height: 1;
  text-align: center;
  text-decoration: none;
}

.btn-primary,
.btn-main {
  min-height: 52px;
  padding-inline: 34px;
  border-color: var(--color-accent);
  background: var(--color-accent);
  box-shadow: var(--shadow-button);
  color: var(--color-white);
}

.btn-primary:hover,
.btn-main:hover {
  border-color: var(--color-accent-deep);
  background: var(--color-accent-deep);
  color: var(--color-white);
  transform: translateY(-1px);
}

.btn-secondary,
.btn-sub {
  min-height: 52px;
  padding-inline: 26px;
  border-color: var(--color-line);
  background: var(--color-canvas);
  color: var(--color-ink);
}

.btn-secondary:hover,
.btn-sub:hover {
  border-color: var(--color-accent-soft);
  background: var(--color-panel);
  color: var(--color-ink);
}

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

.btn-small {
  min-height: 38px;
  padding-inline: 18px;
  font-size: 13px;
}

.btn[aria-disabled="true"],
.btn:disabled {
  border-color: var(--color-line);
  background: var(--color-panel-strong);
  box-shadow: none;
  color: var(--color-ink-muted);
  cursor: not-allowed;
  transform: none;
}

.button-row,
.cta-row {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

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

.head-in {
  position: relative;
  display: flex;
  align-items: center;
  gap: 30px;
  min-height: var(--header-height);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: max-content;
  color: var(--color-ink);
  text-decoration: none;
  flex: 0 0 auto;
}

.brand:hover {
  color: var(--color-ink);
}

.brand-logo {
  width: 30px;
  height: 30px;
  flex: 0 0 auto;
}

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

.brand-local {
  color: var(--color-ink-muted);
  font-size: 14px;
  font-weight: 550;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 24px;
  margin-left: auto;
}

.main-nav a {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  color: var(--color-ink-muted);
  font-size: 13.5px;
  font-weight: 520;
  text-decoration: none;
  white-space: nowrap;
}

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

.main-nav a.is-active,
.main-nav a[aria-current="page"] {
  font-weight: 750;
}

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

.lang-control {
  position: relative;
}

.lang-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-width: 44px;
  min-height: 36px;
  padding: 0 10px;
  border-radius: var(--radius-pill);
  background: var(--color-canvas);
  color: var(--color-ink-muted);
  cursor: pointer;
  font-size: 13px;
}

.lang-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  z-index: 115;
  display: none;
  width: 160px;
  padding: 8px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-medium);
  background: var(--color-canvas);
  box-shadow: var(--shadow-focus);
}

.lang-control.is-open .lang-menu {
  display: block;
}

.lang-menu a {
  display: flex;
  align-items: center;
  min-height: 42px;
  padding: 8px 11px;
  border-radius: var(--radius-small);
  color: var(--color-ink-muted);
  font-size: 13px;
  text-decoration: none;
}

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

.btn-login {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 36px;
  padding: 0 20px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-canvas);
  color: var(--color-accent);
  font-size: 13.5px;
  font-weight: 650;
  text-decoration: none;
  white-space: nowrap;
}

.btn-login:hover {
  border-color: var(--color-accent-soft);
  box-shadow: var(--focus-ring);
  color: var(--color-accent-deep);
}

.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 44px;
  min-width: 44px;
  height: 44px;
  min-height: 44px;
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-ink);
  cursor: pointer;
}

.menu-toggle svg {
  width: 20px;
  height: 20px;
}

.mobile-nav {
  position: absolute;
  top: 100%;
  right: var(--gutter);
  left: var(--gutter);
  z-index: 120;
  display: none;
  max-height: calc(100dvh - var(--header-height) - 16px);
  padding: 10px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-large);
  background: var(--color-canvas);
  box-shadow: var(--shadow-focus);
  overflow-y: auto;
  overscroll-behavior: contain;
}

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

.mobile-nav ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.mobile-nav a {
  display: flex;
  align-items: center;
  width: 100%;
  min-height: 46px;
  padding: 10px 13px;
  border-radius: var(--radius-small);
  color: var(--color-ink-muted);
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
}

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

.mobile-language {
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid var(--color-line);
}

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

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

.site-foot {
  padding-top: 74px;
  padding-bottom: 28px;
  border-top: 1px solid var(--color-line);
  background: var(--color-panel);
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(240px, 1.25fr) repeat(3, minmax(150px, 0.75fr));
  gap: 48px;
}

.footer-brand p {
  max-width: 360px;
  margin-top: 18px;
  color: var(--color-ink-muted);
  font-size: 14px;
}

.footer-title {
  margin-bottom: 15px;
  color: var(--color-ink);
  font-size: 13px;
  font-weight: 750;
}

.footer-links {
  margin: 0;
  padding: 0;
  list-style: none;
}

.footer-links li + li {
  margin-top: 6px;
}

.footer-links a {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  color: var(--color-ink-muted);
  font-size: 13.5px;
  text-decoration: none;
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  margin-top: 54px;
  padding-top: 22px;
  border-top: 1px solid var(--color-line);
  color: var(--color-ink-muted);
  font-size: 12.5px;
}

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

.footer-legal a {
  color: var(--color-ink-muted);
  text-decoration: none;
}

.reveal {
  transition: opacity 600ms ease, transform 600ms ease;
}

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

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

.prose {
  color: var(--color-ink-muted);
  font-size: 16.5px;
}

.prose h2,
.prose h3,
.prose h4 {
  color: var(--color-ink);
  scroll-margin-top: var(--toc-offset);
}

.prose a {
  overflow-wrap: anywhere;
}

.prose img {
  margin: 28px auto;
  border-radius: var(--radius-medium);
}

.prose table {
  width: 100%;
  border-collapse: collapse;
}

.prose th,
.prose td {
  padding: 13px 15px;
  border: 1px solid var(--color-line);
  text-align: left;
  vertical-align: top;
}

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

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 300;
  padding: 10px 14px;
  border-radius: var(--radius-small);
  background: var(--color-accent);
  color: var(--color-white);
  transform: translateY(-150%);
}

.skip-link:focus {
  color: var(--color-white);
  transform: translateY(0);
}

@media (max-width: 1160px) {
  .main-nav {
    display: none;
  }

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

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

  .lang-control {
    display: none;
  }
}

@media (max-width: 768px) {
  :root {
    --gutter: 20px;
    --section-space: 76px;
    --toc-offset: 78px;
  }

  h1 {
    font-size: clamp(34px, 10vw, 40px);
    line-height: 1.12;
  }

  h2 {
    font-size: clamp(29px, 8vw, 38px);
  }

  .section-heading {
    margin-bottom: 38px;
  }

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

  .footer-brand {
    grid-column: 1 / -1;
  }

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

  .btn-login {
    min-width: 62px;
    padding-inline: 14px;
  }
}

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
    --header-height: 62px;
  }

  body {
    overflow-x: clip;
  }

  .head-in {
    gap: 10px;
    min-height: var(--header-height);
  }

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

  .brand-local {
    display: none;
  }

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

  .mobile-nav {
    right: var(--gutter);
    left: var(--gutter);
  }

  .button-row,
  .cta-row {
    align-items: stretch;
    flex-direction: column;
  }

  .button-row .btn,
  .cta-row .btn,
  .cta-row .btn-main,
  .cta-row .btn-sub {
    width: 100%;
  }

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

  .footer-brand {
    grid-column: auto;
  }

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

  .section {
    padding-top: 68px;
    padding-bottom: 68px;
  }

  .section-tight {
    padding-top: 48px;
    padding-bottom: 48px;
  }
}

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

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

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