:root {
  --color-bg: #E8F3F7;
  --color-panel: #F7FCFE;
  --color-panel-strong: #D9EAF1;
  --color-border: #C2DAE4;
  --color-accent: #0E7490;
  --color-accent-dark: #0A5A70;
  --color-text: #14262E;
  --color-text-muted: #4E6B77;
  --color-success: #1A9A64;
  --color-warning: #C07A14;
  --color-error: #C2402E;
  --color-on-accent: #FFFFFF;
  --color-flag-white: #FCFDFD;
  --color-flag-red: #CC4038;
  --color-flag-blue: #31549B;
  --color-flag-navy: #223B72;
  --color-overlay: rgba(20, 38, 46, 0.34);
  --color-accent-soft: rgba(14, 116, 144, 0.10);
  --color-accent-medium: rgba(14, 116, 144, 0.16);
  --color-success-soft: rgba(26, 154, 100, 0.18);
  --color-shadow-soft: rgba(20, 38, 46, 0.05);
  --color-shadow-medium: rgba(14, 116, 144, 0.10);
  --color-shadow-button: rgba(14, 116, 144, 0.28);
  --color-shadow-window: rgba(20, 38, 46, 0.20);
  --color-knob-shadow: rgba(20, 38, 46, 0.25);
  --font-display: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  --radius-xl: 28px;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 9px;
  --radius-pill: 999px;
  --shadow-card: 0 2px 6px var(--color-shadow-soft), 0 16px 38px var(--color-shadow-medium);
  --shadow-window: 0 10px 26px var(--color-accent-medium), 0 46px 92px var(--color-shadow-window);
  --shadow-button: 0 6px 18px var(--color-shadow-button);
  --content-width: 1360px;
  --reading-width: 780px;
  --gutter: 40px;
  --header-height: 76px;
  --section-space: 96px;
  --toc-offset: 96px;
  --transition-fast: 180ms ease;
  --transition-reveal: 620ms cubic-bezier(0.22, 1, 0.36, 1);
}

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

html {
  min-width: 320px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  margin: 0;
  overflow-x: clip;
  color: var(--color-text);
  background-color: var(--color-bg);
  background-image:
    radial-gradient(880px 560px at 76% 8%, var(--color-accent-medium), transparent 62%),
    radial-gradient(720px 520px at 6% 92%, var(--color-accent-soft), transparent 60%);
  background-repeat: no-repeat;
  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 {
  font: inherit;
}

button,
summary {
  color: inherit;
}

button {
  border: 0;
  cursor: pointer;
}

a {
  color: var(--color-accent-dark);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.18em;
}

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

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

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

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

h1,
h2,
h3,
h4 {
  margin-top: 0;
  color: var(--color-text);
  font-family: var(--font-display);
  line-height: 1.18;
  text-wrap: balance;
}

h1 {
  margin-bottom: 20px;
  font-size: clamp(52px, 5vw, 72px);
  font-weight: 800;
  letter-spacing: -0.018em;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(34px, 3.5vw, 50px);
  font-weight: 760;
  letter-spacing: -0.012em;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(23px, 2.2vw, 30px);
  font-weight: 720;
}

h4 {
  margin-bottom: 10px;
  font-size: 19px;
  font-weight: 700;
}

strong {
  font-weight: 720;
}

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

code {
  overflow-wrap: anywhere;
  border-radius: var(--radius-sm);
  background: var(--color-panel-strong);
  padding: 0.12em 0.36em;
  font-size: 0.9em;
}

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

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

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

::selection {
  color: var(--color-on-accent);
  background: var(--color-accent);
}

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

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

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

.section-compact {
  padding-top: calc(var(--section-space) / 2);
  padding-bottom: calc(var(--section-space) / 2);
}

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

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

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

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  max-width: 100%;
  margin: 0 0 22px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  padding: 7px 16px;
  color: var(--color-accent-dark);
  font-size: 13px;
  font-weight: 650;
}

.eyebrow-dot,
.status-dot {
  width: 8px;
  height: 8px;
  flex: 0 0 auto;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
}

.status-dot.is-online {
  background: var(--color-success);
  box-shadow: 0 0 0 4px var(--color-success-soft);
}

.badge,
.fact-chip,
.tag-chip {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  gap: 7px;
  max-width: 100%;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  padding: 5px 12px;
  color: var(--color-accent-dark);
  font-size: 12.5px;
  font-weight: 650;
  line-height: 1.35;
  overflow-wrap: anywhere;
}

.tag-chip {
  overflow: hidden;
}

.fact-chip::before {
  content: "✓";
  flex: 0 0 auto;
  color: var(--color-success);
  font-weight: 800;
}

.btn,
.button {
  display: inline-flex;
  min-width: 24px;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 1.5px solid transparent;
  border-radius: var(--radius-pill);
  padding: 12px 30px;
  font-weight: 720;
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  transition:
    transform var(--transition-fast),
    color var(--transition-fast),
    background-color var(--transition-fast),
    border-color var(--transition-fast),
    box-shadow var(--transition-fast);
}

.btn-primary {
  color: var(--color-on-accent);
  background: var(--color-accent);
  box-shadow: var(--shadow-button);
}

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

.btn-secondary,
.btn-ghost {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: var(--color-panel);
}

.btn-secondary:hover,
.btn-ghost:hover {
  color: var(--color-accent-dark);
  background: var(--color-accent-soft);
  transform: translateY(-1px);
}

.btn-muted {
  border-color: var(--color-border);
  color: var(--color-text-muted);
  background: var(--color-panel-strong);
}

.btn[aria-disabled="true"],
.btn:disabled {
  cursor: not-allowed;
  box-shadow: none;
  opacity: 0.58;
  transform: none;
}

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

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

.card {
  padding: 28px;
}

.card-subtle {
  border-radius: var(--radius-lg);
  background: var(--color-panel-strong);
  padding: 28px;
}

.grid {
  display: grid;
  gap: 24px;
}

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

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

.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid-4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

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

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

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

.site-header {
  position: relative;
  z-index: 50;
  min-height: var(--header-height);
}

.header-shell {
  display: flex;
  min-height: var(--header-height);
  align-items: center;
  gap: 24px;
}

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

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

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

.brand-word {
  color: var(--color-text);
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 760;
  letter-spacing: 0.01em;
}

.brand-local {
  color: var(--color-text-muted);
  font-size: 14px;
  font-weight: 560;
}

.desktop-nav {
  display: flex;
  align-items: center;
  gap: 3px;
}

.desktop-nav a {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  border-radius: var(--radius-pill);
  padding: 7px 13px;
  color: var(--color-text-muted);
  font-size: 14px;
  text-decoration: none;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

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

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

.header-tools {
  position: relative;
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 10px;
  margin-left: auto;
}

.language-menu {
  position: relative;
}

.language-button {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 6px;
  border-radius: var(--radius-pill);
  background: transparent;
  padding: 7px 10px;
  color: var(--color-text-muted);
  font-size: 13px;
}

.language-popover {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 70;
  display: none;
  width: 168px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-panel);
  box-shadow: var(--shadow-card);
  padding: 7px;
}

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

.language-popover a {
  display: flex;
  min-height: 42px;
  align-items: center;
  border-radius: var(--radius-sm);
  padding: 8px 11px;
  color: var(--color-text-muted);
  text-decoration: none;
}

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

.login-link {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  justify-content: center;
  border: 1.5px solid var(--color-accent);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  padding: 7px 20px;
  color: var(--color-accent);
  font-size: 14px;
  font-weight: 680;
  text-decoration: none;
}

.login-link:hover {
  color: var(--color-on-accent);
  background: var(--color-accent);
}

.menu-toggle {
  display: none;
  width: 44px;
  min-width: 44px;
  height: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
}

.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-text);
}

.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;
}

.mobile-nav {
  position: fixed;
  top: var(--header-height);
  right: 0;
  left: 0;
  z-index: 65;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  overflow-y: auto;
  overscroll-behavior: contain;
  border-top: 1px solid var(--color-border);
  background: var(--color-panel);
  padding: 12px var(--gutter) 22px;
}

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

.mobile-nav a {
  display: flex;
  width: 100%;
  min-height: 48px;
  align-items: center;
  border-radius: var(--radius-md);
  padding: 11px 14px;
  color: var(--color-text-muted);
  text-decoration: none;
}

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

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

.mobile-language-links {
  margin-top: 12px;
  border-top: 1px solid var(--color-border);
  padding-top: 12px;
}

.nav-veil {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 40;
  display: none;
  background: var(--color-overlay);
}

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

.site-footer {
  margin-top: var(--section-space);
  overflow-x: clip;
  border-top: 1px solid var(--color-border);
  background: var(--color-panel-strong);
}

.footer-main {
  display: grid;
  grid-template-columns: minmax(240px, 1.15fr) repeat(3, minmax(160px, 0.85fr));
  gap: 42px;
  padding-top: 62px;
  padding-bottom: 48px;
}

.footer-brand-copy {
  max-width: 390px;
  margin-top: 18px;
  color: var(--color-text-muted);
}

.footer-title {
  margin-bottom: 15px;
  font-size: 14px;
  font-weight: 760;
}

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

.footer-links a {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  width: fit-content;
  color: var(--color-text-muted);
  font-size: 14px;
  text-decoration: none;
}

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

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  border-top: 1px solid var(--color-border);
  padding-top: 20px;
  padding-bottom: 26px;
  color: var(--color-text-muted);
  font-size: 13px;
}

.footer-legal,
.footer-languages {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 18px;
}

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

@media (max-width: 1180px) {
  .desktop-nav a {
    padding-inline: 9px;
    font-size: 13px;
  }

  .language-menu {
    display: none;
  }
}

@media (max-width: 920px) {
  :root {
    --gutter: 24px;
    --section-space: 76px;
  }

  .desktop-nav {
    display: none;
  }

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

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

  .grid-4,
  .grid-3 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

@media (max-width: 768px) {
  h1 {
    font-size: clamp(32px, 9.5vw, 40px);
    line-height: 1.12;
  }

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

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .brand-local {
    display: none;
  }
}

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
    --header-height: 68px;
    --section-space: 62px;
    --toc-offset: 84px;
  }

  .header-shell {
    min-height: var(--header-height);
    gap: 8px;
  }

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

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

  .login-link {
    min-height: 38px;
    padding-inline: 14px;
  }

  .mobile-nav {
    padding-inline: var(--gutter);
  }

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

  .card,
  .card-subtle {
    padding: 22px;
  }

  .decorative-tilt,
  .tilt-card {
    transform: none !important;
  }

  .footer-main {
    grid-template-columns: 1fr;
    gap: 30px;
    padding-top: 48px;
  }

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

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0s !important;
    animation-duration: 0s !important;
  }

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