:root {
  --color-bg: #FFFFFF;
  --color-panel: #F7F8F8;
  --color-panel-strong: #EFF2F1;
  --color-border: #E4E7E6;
  --color-accent: #257D78;
  --color-accent-dark: #1A5B57;
  --color-text: #111415;
  --color-text-muted: #5D6664;
  --color-success: #2F8A5B;
  --color-warning: #B9862E;
  --color-error: #BE4438;
  --color-flag-blue: #3A5490;
  --color-flag-gold: #CFA24A;
  --color-overlay: rgba(17, 20, 21, 0.42);
  --color-shadow: rgba(17, 20, 21, 0.14);
  --font-display: 'Inter', 'Noto Sans SC', -apple-system, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;
  --radius-pill: 999px;
  --radius-xl: 30px;
  --radius-lg: 22px;
  --radius-md: 14px;
  --radius-sm: 8px;
  --shadow-float: 0 10px 26px var(--color-shadow);
  --content-wide: 1360px;
  --content-main: 1120px;
  --content-prose: 760px;
  --gutter: clamp(16px, 3vw, 28px);
  --header-height: 63px;
  --toc-offset: 82px;
  --duration-fast: 160ms;
  --duration-reveal: 560ms;
  --ease-standard: cubic-bezier(0.22, 1, 0.36, 1);
}

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

html {
  min-width: 320px;
  scroll-behavior: smooth;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  text-size-adjust: 100%;
}

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;
}

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

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

img {
  height: auto;
}

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

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

button {
  cursor: pointer;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

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

h1,
h2,
h3,
h4 {
  color: var(--color-text);
  font-family: var(--font-display);
  font-weight: 500;
  line-height: 1.2;
  text-wrap: balance;
}

h1,
.hero-title {
  margin-bottom: 20px;
  font-size: clamp(52px, 5vw, 72px);
  font-weight: 420;
  line-height: 1.14;
  letter-spacing: 0.005em;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(32px, 4vw, 48px);
  letter-spacing: -0.01em;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2.5vw, 28px);
}

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

p {
  margin-bottom: 1em;
}

strong {
  font-weight: 650;
}

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

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

:not(pre) > code {
  max-width: 100%;
  padding: 0.12em 0.36em;
  overflow-wrap: anywhere;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-panel);
  font-size: 0.9em;
}

pre {
  max-width: 100%;
  margin: 24px 0;
  padding: 18px;
  overflow-x: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-panel);
  color: var(--color-text);
  line-height: 1.65;
  -webkit-overflow-scrolling: touch;
}

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

hr {
  height: 1px;
  margin: 36px 0;
  border: 0;
  background: var(--color-border);
}

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

:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 3px;
}

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

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

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

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

.section {
  padding-top: clamp(70px, 9vw, 128px);
  padding-bottom: clamp(70px, 9vw, 128px);
}

.section-compact {
  padding-top: clamp(44px, 6vw, 80px);
  padding-bottom: clamp(44px, 6vw, 80px);
}

.section-head {
  max-width: 760px;
  margin-bottom: 42px;
}

.section-kicker,
.eyebrow {
  margin-bottom: 12px;
  color: var(--color-accent-dark);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.lead {
  color: var(--color-text-muted);
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.7;
}

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

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

.nowrap-term {
  white-space: nowrap;
}

.stack {
  display: grid;
  gap: 20px;
}

.cluster {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}

.cluster > svg,
.cluster > img,
.cluster > .dot,
.cluster > .icon {
  flex-shrink: 0;
}

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

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

.card {
  padding: 24px;
}

.paper-panel {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  background: var(--color-bg);
}

.tilt,
.tilt-soft {
  transform: rotate(-0.35deg);
}

.btn,
.btn-main,
.btn-sub,
.btn-dark,
.btn-quiet {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  max-width: 100%;
  padding: 11px 24px;
  border: 1px solid transparent;
  border-radius: 12px;
  font-weight: 600;
  line-height: 1.2;
  text-align: center;
  transition:
    color var(--duration-fast),
    background-color var(--duration-fast),
    border-color var(--duration-fast),
    transform var(--duration-fast);
}

.btn svg,
.btn-main svg,
.btn-sub svg,
.btn-dark svg,
.btn-quiet svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

.btn-main {
  border-color: var(--color-accent);
  background: var(--color-accent);
  color: var(--color-bg);
}

.btn-main:hover {
  border-color: var(--color-accent-dark);
  background: var(--color-accent-dark);
}

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

.btn-sub:hover {
  border-color: var(--color-accent);
  color: var(--color-accent-dark);
}

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

.btn-dark:hover {
  border-color: var(--color-accent-dark);
  background: var(--color-accent-dark);
}

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

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

.btn[aria-disabled="true"],
.btn:disabled,
.btn-main:disabled,
.btn-sub:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.badge,
.tag,
.trust-chip {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  max-width: 100%;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-bg);
  color: var(--color-text-muted);
  font-size: 12px;
  line-height: 1.25;
}

.badge,
.tag {
  padding: 6px 11px;
  overflow: hidden;
  overflow-wrap: anywhere;
}

.trust-chip {
  padding: 6px 13px;
}

.status-dot,
.badge-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-error {
  background: var(--color-error);
}

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

.header-row {
  width: 100%;
  max-width: var(--content-wide);
  height: var(--header-height);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 18px;
}

.site-brand {
  display: inline-flex;
  flex: none;
  align-items: center;
  gap: 9px;
  min-height: 44px;
}

.site-brand img {
  width: 27px;
  height: 27px;
  flex-shrink: 0;
}

.brand-word {
  color: var(--color-text);
  font-size: 17px;
  font-weight: 720;
  letter-spacing: 0.01em;
}

.brand-local {
  color: var(--color-text-muted);
  font-size: 14px;
  font-weight: 450;
}

.desktop-nav {
  display: flex;
  flex: 1 1 auto;
  align-items: center;
  gap: 2px;
  min-width: 0;
  margin-left: 8px;
}

.desktop-nav a {
  padding: 7px 10px;
  border-radius: var(--radius-pill);
  color: var(--color-text-muted);
  font-size: 13px;
  white-space: nowrap;
  transition:
    color var(--duration-fast),
    background-color var(--duration-fast);
}

.desktop-nav a:hover {
  background: var(--color-panel);
  color: var(--color-text);
}

.desktop-nav a.is-active {
  background: var(--color-panel-strong);
  color: var(--color-accent-dark);
  font-weight: 650;
}

.header-tools {
  display: flex;
  flex: none;
  align-items: center;
  gap: 9px;
}

.language-menu {
  position: relative;
}

.language-toggle {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  gap: 6px;
  padding: 7px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-bg);
  color: var(--color-text-muted);
  font-size: 12px;
}

.language-toggle:hover,
.language-toggle[aria-expanded="true"] {
  border-color: var(--color-text-muted);
  color: var(--color-text);
}

.language-popover {
  position: absolute;
  top: calc(100% + 9px);
  right: 0;
  z-index: 130;
  display: none;
  width: 168px;
  padding: 7px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg);
  box-shadow: var(--shadow-float);
}

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

.language-popover a {
  display: flex;
  min-height: 42px;
  align-items: center;
  padding: 8px 11px;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  font-size: 13px;
}

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

.header-login {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  justify-content: center;
  padding: 8px 17px;
  border-radius: var(--radius-pill);
  background: var(--color-text);
  color: var(--color-bg);
  font-size: 13px;
  font-weight: 650;
  white-space: nowrap;
}

.header-login:hover {
  background: var(--color-accent-dark);
}

.menu-toggle {
  display: none;
  min-width: 44px;
  min-height: 44px;
  padding: 10px;
  border: 0;
  border-radius: var(--radius-pill);
  background: var(--color-panel);
}

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  display: block;
  width: 19px;
  height: 2px;
  border-radius: var(--radius-pill);
  background: var(--color-text);
}

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

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

.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 {
  top: 0;
  transform: rotate(45deg);
}

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

.mobile-nav {
  position: absolute;
  top: var(--header-height);
  right: 0;
  left: 0;
  z-index: 125;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  padding: 12px var(--gutter) 22px;
  overflow-y: auto;
  overscroll-behavior: contain;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
}

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

.mobile-nav a {
  display: flex;
  width: 100%;
  min-height: 46px;
  align-items: center;
  padding: 10px 13px;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
}

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

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

.mobile-language-label {
  padding: 7px 13px;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

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

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

.site-footer {
  margin-top: clamp(70px, 10vw, 140px);
  border-top: 1px solid var(--color-border);
  background: var(--color-panel);
}

.footer-main {
  display: grid;
  grid-template-columns: minmax(220px, 1.25fr) repeat(3, minmax(150px, 1fr));
  gap: 42px;
  padding-top: 58px;
  padding-bottom: 48px;
}

.footer-brand {
  max-width: 340px;
}

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

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

.footer-title {
  margin-bottom: 14px;
  font-size: 13px;
  font-weight: 700;
}

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

.footer-links a {
  color: var(--color-text-muted);
  font-size: 13px;
  overflow-wrap: anywhere;
}

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

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding-top: 20px;
  padding-bottom: 26px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 12px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

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

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

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

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

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

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

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

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

.prose a {
  color: var(--color-accent-dark);
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-underline-offset: 3px;
}

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

.prose li + li {
  margin-top: 0.45em;
}

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

@media (max-width: 1180px) {
  .desktop-nav a {
    padding-inline: 7px;
    font-size: 12px;
  }

  .language-toggle {
    padding-inline: 10px;
  }
}

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

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

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

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

@media (max-width: 768px) {
  h1,
  .hero-title {
    font-size: clamp(28px, 9.5vw, 40px);
    line-height: 1.14;
    letter-spacing: -0.01em;
  }

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

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

  .header-row {
    gap: 10px;
  }

  .brand-local {
    display: none;
  }

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

  .footer-main {
    gap: 32px 24px;
  }
}

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
    --header-height: 59px;
  }

  body {
    overflow-x: clip;
  }

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

  .wrap,
  .wrap-wide,
  .prose-wrap {
    padding-inline: var(--gutter);
  }

  .btn,
  .btn-main,
  .btn-sub,
  .btn-dark,
  .btn-quiet {
    white-space: normal;
  }

  .header-row {
    height: var(--header-height);
  }

  .site-brand img {
    width: 25px;
    height: 25px;
  }

  .brand-word {
    font-size: 16px;
  }

  .header-login {
    min-height: 36px;
    padding: 7px 12px;
  }

  .mobile-nav {
    top: var(--header-height);
  }

  .nav-veil {
    inset-top: var(--header-height);
  }

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

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

@media (max-width: 380px) {
  .header-row {
    gap: 7px;
  }

  .header-login {
    padding-inline: 10px;
    font-size: 12px;
  }

  .menu-toggle {
    min-width: 44px;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }

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