:root {
  --color-bg: #FFFFFF;
  --color-panel: #F5F7FE;
  --color-ink: #0E1330;
  --color-line: #E3E8F5;
  --color-accent: #2456F0;
  --color-accent-strong: #173CB4;
  --color-accent-soft: #E2EAFE;
  --color-text: #10142B;
  --color-muted: #5A617A;
  --color-success: #0E9F6E;
  --color-warning: #D97706;
  --color-error: #DC2626;
  --color-inverse: #F4F6FF;
  --color-inverse-muted: #9BA3C4;
  --color-inverse-line: rgba(155, 163, 196, .22);
  --color-dot-grid: rgba(155, 163, 196, .14);
  --color-shadow: rgba(16, 20, 43, .10);
  --color-shadow-deep: rgba(16, 20, 43, .20);
  --color-accent-shadow: rgba(36, 86, 240, .30);
  --color-success-ring: rgba(14, 159, 110, .16);
  --color-overlay: rgba(14, 19, 48, .48);
  --color-code: #EEF2FF;
  --color-mac-red: #FF5F57;
  --color-mac-yellow: #FEBC2E;
  --color-mac-green: #28C840;
  --color-flag-white: #FFFFFF;
  --color-flag-red: #D80027;
  --color-flag-blue: #0052B4;
  --color-flag-navy: #1A2B6B;

  --font-display: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Hiragino Sans', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Hiragino Sans', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, 'SF Mono', 'Cascadia Mono', Consolas, monospace;

  --radius-pill: 999px;
  --radius-xl: 18px;
  --radius-lg: 14px;
  --radius-md: 10px;
  --radius-sm: 6px;

  --shadow-window: 0 2px 6px rgba(16, 20, 43, .06), 0 30px 70px var(--color-shadow-deep);
  --shadow-soft: 0 10px 28px var(--color-shadow);
  --shadow-cta: 0 8px 22px var(--color-accent-shadow);

  --header-height: 66px;
  --content-max: 1328px;
  --reading-max: 820px;
  --gutter: 32px;
  --section-space: 104px;
  --focus-width: 2px;
  --toc-offset: 132px;
  --transition-fast: 150ms ease;
  --transition-reveal: 560ms cubic-bezier(.2, .7, .2, 1);
}

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

html {
  background: var(--color-bg);
  color: var(--color-text);
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
  text-size-adjust: 100%;
}

html.nav-open {
  overflow: hidden;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: clip;
}

body:has(.float-cta)::after {
  content: "";
  display: block;
  height: calc(88px + env(safe-area-inset-bottom, 0px));
}

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

img {
  height: auto;
}

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

button,
summary {
  cursor: pointer;
}

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

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

ul,
ol {
  padding-left: 1.25rem;
}

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

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

h1 {
  margin-bottom: 24px;
  font-size: clamp(52px, 4.65vw, 68px);
  font-weight: 800;
  letter-spacing: -.02em;
  line-height: 1.1;
}

h2 {
  margin-bottom: 20px;
  font-size: clamp(34px, 3vw, 48px);
  font-weight: 800;
  letter-spacing: -.018em;
  line-height: 1.16;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2vw, 28px);
  font-weight: 750;
  line-height: 1.3;
}

p {
  margin-bottom: 1.15em;
}

strong {
  color: var(--color-text);
}

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

code {
  overflow-wrap: anywhere;
  padding: .12em .35em;
  border-radius: var(--radius-sm);
  background: var(--color-code);
}

pre {
  max-width: 100%;
  margin: 24px 0;
  padding: 20px;
  overflow-x: auto;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-ink);
  color: var(--color-inverse);
  -webkit-overflow-scrolling: touch;
}

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

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

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

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

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

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

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

.section-heading {
  max-width: 760px;
  margin-bottom: 44px;
}

.section-heading p {
  color: var(--color-muted);
  font-size: 18px;
}

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

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

.eyebrow {
  display: inline-flex;
  min-height: 30px;
  max-width: 100%;
  align-items: center;
  gap: 8px;
  padding: 5px 13px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-muted);
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .06em;
}

.status-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: var(--radius-pill);
  background: var(--color-success);
  box-shadow: 0 0 0 3px var(--color-success-ring);
}

.badge {
  display: inline-flex;
  min-height: 26px;
  max-width: 100%;
  align-items: center;
  justify-content: center;
  padding: 3px 10px;
  overflow: hidden;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-muted);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
}

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

.badge-success {
  color: var(--color-success);
}

.btn {
  display: inline-flex;
  min-height: 48px;
  min-width: 24px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 28px;
  border: 1.5px solid transparent;
  border-radius: var(--radius-pill);
  font-weight: 700;
  line-height: 1.2;
  text-align: center;
  cursor: pointer;
  transition: color var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

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

.btn-primary {
  border-color: var(--color-accent);
  background: var(--color-accent);
  color: var(--color-bg);
  box-shadow: var(--shadow-cta);
}

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

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

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

.btn-dark {
  border-color: var(--color-inverse-line);
  background: var(--color-ink);
  color: var(--color-inverse);
}

.btn-small {
  min-height: 38px;
  padding: 8px 18px;
  font-size: 14px;
}

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

.card {
  padding: 28px;
  box-shadow: 0 1px 0 var(--color-line), var(--shadow-soft);
}

.panel {
  padding: 32px;
  background: var(--color-panel);
}

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

.dark-section {
  position: relative;
  overflow-x: clip;
  background-color: var(--color-ink);
  background-image: radial-gradient(var(--color-dot-grid) 1px, transparent 1px);
  background-size: 20px 20px;
  color: var(--color-inverse);
}

.dark-section h1,
.dark-section h2,
.dark-section h3,
.dark-section strong {
  color: var(--color-inverse);
}

.dark-section .muted,
.dark-section p {
  color: var(--color-inverse-muted);
}

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

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

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

.site-header {
  position: relative;
  z-index: 80;
  height: var(--header-height);
  border-bottom: 1px solid var(--color-line);
  background: var(--color-bg);
}

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

.brand-link {
  display: inline-flex;
  min-width: 0;
  min-height: 44px;
  flex: 0 0 auto;
  align-items: center;
  gap: 10px;
}

.brand-logo {
  width: 34px;
  height: 34px;
  flex: 0 0 auto;
  border-radius: 8px;
}

.brand-copy {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  white-space: nowrap;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  letter-spacing: -.01em;
}

.brand-local {
  color: var(--color-muted);
  font-size: 12px;
  font-weight: 500;
}

.desktop-nav {
  align-self: stretch;
}

.nav-tabs {
  display: flex;
  height: 100%;
  align-items: stretch;
  gap: 2px;
}

.nav-tabs a {
  position: relative;
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  padding-inline: 12px;
  color: var(--color-muted);
  font-size: 14px;
  transition: color var(--transition-fast);
}

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

.nav-tabs a.is-active {
  font-weight: 650;
}

.nav-tabs a.is-active::after {
  content: "";
  position: absolute;
  right: 11px;
  bottom: -1px;
  left: 11px;
  height: 3px;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
}

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

.language-control {
  position: relative;
}

.language-button,
.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-button {
  gap: 5px;
  padding-inline: 8px;
  font-size: 13px;
}

.language-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  width: 164px;
  margin: 0;
  padding: 7px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-bg);
  box-shadow: var(--shadow-soft);
  list-style: none;
}

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

.language-menu a {
  display: flex;
  min-height: 40px;
  align-items: center;
  padding: 8px 11px;
  border-radius: var(--radius-sm);
  color: var(--color-muted);
  font-size: 13px;
}

.language-menu a:hover,
.language-menu 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: 7px 18px;
  border: 1.5px solid var(--color-text);
  border-radius: var(--radius-pill);
  color: var(--color-text);
  font-size: 14px;
  font-weight: 650;
  transition: color var(--transition-fast), background var(--transition-fast);
}

.header-login:hover {
  background: var(--color-text);
  color: var(--color-bg);
}

.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
}

.menu-toggle span {
  width: 19px;
  height: 2px;
  border-radius: var(--radius-pill);
  background: var(--color-text);
}

.mobile-nav {
  display: none;
}

.nav-veil {
  display: none;
}

.site-footer {
  position: relative;
  overflow-x: clip;
  border-top: 1px solid var(--color-inverse-line);
  background-color: var(--color-ink);
  background-image: radial-gradient(var(--color-dot-grid) 1px, transparent 1px);
  background-size: 20px 20px;
  color: var(--color-inverse-muted);
}

.footer-main {
  display: grid;
  grid-template-columns: minmax(240px, 1.3fr) repeat(3, minmax(150px, 1fr));
  gap: 46px;
  padding-top: 68px;
  padding-bottom: 52px;
}

.footer-brand {
  max-width: 330px;
}

.footer-brand .brand-name,
.footer-brand strong,
.footer-title {
  color: var(--color-inverse);
}

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

.footer-title {
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
}

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

.footer-links a {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  color: var(--color-inverse-muted);
  font-size: 14px;
}

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

.footer-bottom {
  display: flex;
  padding-top: 20px;
  padding-bottom: 24px;
  border-top: 1px solid var(--color-inverse-line);
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  font-size: 12px;
}

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

.prose {
  min-width: 0;
  color: var(--color-text);
  font-size: 17px;
}

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

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

.prose a:not(.btn) {
  color: var(--color-accent-strong);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.prose img {
  border-radius: var(--radius-md);
}

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

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

  *,
  *::before,
  *::after {
    transition-duration: 0s !important;
    animation-duration: 0s !important;
    animation-iteration-count: 1 !important;
  }

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

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

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

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

  .mobile-nav {
    position: absolute;
    z-index: 92;
    top: var(--header-height);
    right: 0;
    left: 0;
    max-height: calc(100dvh - var(--header-height));
    padding: 12px var(--gutter) 20px;
    overflow-y: auto;
    overscroll-behavior: contain;
    border-bottom: 1px solid var(--color-line);
    background: var(--color-bg);
    box-shadow: var(--shadow-soft);
  }

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

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

  .mobile-nav a {
    display: flex;
    width: 100%;
    min-height: 48px;
    align-items: center;
    padding: 11px 8px;
    border-bottom: 1px solid var(--color-line);
    color: var(--color-muted);
  }

  .mobile-nav a.is-active {
    color: var(--color-accent-strong);
    font-weight: 700;
  }

  .mobile-languages {
    margin-top: 12px !important;
  }

  .nav-veil {
    position: fixed;
    z-index: 70;
    inset: var(--header-height) 0 0;
    background: var(--color-overlay);
  }

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

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

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

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

  h1 {
    font-size: clamp(34px, 10vw, 40px);
    line-height: 1.12;
    letter-spacing: -.018em;
  }

  h2 {
    font-size: clamp(28px, 8vw, 36px);
  }

  .section-heading p,
  .prose {
    font-size: 16px;
  }

  .header-inner {
    gap: 12px;
  }

  .brand-local,
  .language-button span {
    display: none;
  }

  .header-login {
    min-height: 36px;
    padding-inline: 14px;
  }

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

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

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

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

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

  .card,
  .panel {
    padding: 22px;
  }

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

  .decor-orb,
  .decor-disc,
  .decor-watermark {
    display: none;
  }

  .btn {
    padding-inline: 22px;
  }
}

@media (max-width: 390px) {
  .brand-logo {
    width: 31px;
    height: 31px;
  }

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

  .language-control {
    display: none;
  }

  .header-tools {
    gap: 4px;
  }
}