:root {
  --color-bg: #FDF7EA;
  --color-panel: #FFFDF8;
  --color-panel-deep: #F5EBD6;
  --color-border: #E6D9BF;
  --color-accent: #1D9BE8;
  --color-accent-dark: #126FB0;
  --color-text: #2B2117;
  --color-muted: #75665A;
  --color-success: #2E9A5E;
  --color-warning: #E39A1B;
  --color-error: #D8433B;
  --color-peach: #FBDCD1;
  --color-lavender: #E6DFF8;
  --color-butter: #FBECBF;
  --color-mint: #D7F0E1;
  --color-flag-red: #D9463C;
  --color-flag-blue: #2F4E9E;
  --color-white: #FFFFFF;
  --color-grid: rgba(43, 33, 23, 0.045);
  --color-nav: rgba(253, 247, 234, 0.88);
  --color-ink-06: rgba(43, 33, 23, 0.06);
  --color-ink-10: rgba(43, 33, 23, 0.10);
  --color-ink-14: rgba(43, 33, 23, 0.14);
  --color-ink-18: rgba(43, 33, 23, 0.18);
  --color-ink-22: rgba(43, 33, 23, 0.22);
  --color-white-45: rgba(255, 255, 255, 0.45);
  --color-accent-glow: rgba(29, 155, 232, 0.28);
  --font-display: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', system-ui, sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Menlo, Consolas, 'Liberation Mono', monospace;
  --radius-xl: 22px;
  --radius-lg: 18px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --radius-pill: 999px;
  --shadow-card: 0 1px 2px var(--color-ink-06), 0 16px 36px -16px var(--color-ink-18);
  --shadow-card-hover: 0 2px 4px var(--color-ink-06), 0 22px 44px -18px var(--color-ink-22);
  --shadow-button: 0 1px 2px var(--color-ink-10), 0 10px 22px -10px var(--color-accent-glow);
  --shadow-small: 0 1px 2px var(--color-ink-06), 0 8px 18px -10px var(--color-ink-18);
  --content-max: 1360px;
  --reading-max: 780px;
  --gutter: 40px;
  --header-height: 72px;
  --anchor-offset: 132px;
  --transition-fast: 180ms ease;
  --transition-card: 250ms ease;
}

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

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

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  color: var(--color-text);
  background-color: var(--color-bg);
  background-image:
    linear-gradient(var(--color-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-grid) 1px, transparent 1px);
  background-position: center top;
  background-size: 56px 56px;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: clip;
}

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

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

svg {
  display: block;
  flex-shrink: 0;
}

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

button,
summary {
  color: inherit;
}

button {
  cursor: pointer;
}

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

p,
ul,
ol,
blockquote,
figure {
  margin-top: 0;
}

ul[class],
ol[class] {
  margin: 0;
  padding: 0;
  list-style: none;
}

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

h1 {
  max-width: 15em;
  margin-bottom: 24px;
  font-size: clamp(52px, 5vw, 68px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.1;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(32px, 3.5vw, 48px);
  font-weight: 800;
  letter-spacing: -0.018em;
  line-height: 1.16;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2vw, 28px);
  font-weight: 800;
  letter-spacing: -0.012em;
  line-height: 1.25;
}

h4 {
  margin-bottom: 8px;
  font-size: 18px;
  font-weight: 750;
  line-height: 1.35;
}

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-border);
  border-radius: var(--radius-md);
  background: var(--color-panel-deep);
  -webkit-overflow-scrolling: touch;
}

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

hr {
  border: 0;
  border-top: 1px solid var(--color-border);
}

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

:where(a, button, input, select, textarea, summary, [role='tab']):focus-visible {
  outline: 2px 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: 96px;
  padding-bottom: 96px;
}

.section-compact {
  padding-top: 56px;
  padding-bottom: 56px;
}

.section-head {
  max-width: 760px;
  margin-bottom: 38px;
}

.section-head p,
.lead {
  color: var(--color-muted);
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.65;
}

.eyebrow,
.badge,
.pill {
  display: inline-flex;
  min-height: 28px;
  max-width: 100%;
  align-items: center;
  gap: 8px;
  padding: 4px 11px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel-deep);
  color: var(--color-text);
  font-size: 13px;
  font-weight: 650;
  line-height: 1.25;
}

.eyebrow-dot,
.status-dot {
  width: 8px;
  height: 8px;
  flex-shrink: 0;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-glow);
}

.eyebrow-accent {
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: lowercase;
}

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

.badge-warning {
  color: var(--color-text);
  background: var(--color-butter);
}

.badge-accent {
  color: var(--color-accent-dark);
  background: var(--color-lavender);
}

.panel,
.card {
  border: 1px solid var(--color-white-45);
  border-radius: var(--radius-xl);
  background: var(--color-panel);
  box-shadow: var(--shadow-card);
}

.card {
  transition: transform var(--transition-card), box-shadow var(--transition-card);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-card-hover);
}

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

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

.tone-peach {
  background: var(--color-peach);
}

.tone-lavender {
  background: var(--color-lavender);
}

.tone-butter {
  background: var(--color-butter);
}

.tone-mint {
  background: var(--color-mint);
}

.btn {
  display: inline-flex;
  min-width: 24px;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 24px;
  border: 1.5px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 15px;
  font-weight: 750;
  line-height: 1.2;
  text-align: center;
  white-space: nowrap;
  transition: color var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

.btn svg {
  width: 18px;
  height: 18px;
}

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

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

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

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

.btn-soft {
  border-color: var(--color-border);
  background: var(--color-panel-deep);
}

.btn-soft:hover {
  border-color: var(--color-text);
}

.btn[aria-disabled='true'],
.btn:disabled {
  cursor: not-allowed;
  opacity: 0.52;
  transform: none;
}

.text-link {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  gap: 6px;
  border-bottom: 1.5px solid var(--color-border);
  color: var(--color-text);
  font-weight: 700;
}

.text-link:hover {
  color: var(--color-accent-dark);
  border-color: var(--color-accent-dark);
}

.site-head {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-nav);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}

.head-row {
  position: relative;
  display: flex;
  min-height: var(--header-height);
  align-items: center;
  gap: 20px;
}

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

.brand-logo {
  width: 34px;
  height: 34px;
  flex-shrink: 0;
  border-radius: var(--radius-sm);
  box-shadow: 0 6px 14px -6px var(--color-accent-glow);
}

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

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

.main-nav {
  display: flex;
  flex: 1 1 auto;
  align-items: center;
  justify-content: center;
  gap: 2px;
}

.nav-link {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  gap: 6px;
  padding: 8px 9px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-weight: 550;
  line-height: 1.2;
  white-space: nowrap;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.nav-link svg {
  width: 16px;
  height: 16px;
  color: var(--color-muted);
}

.nav-link:hover,
.nav-link.is-active {
  background: var(--color-panel-deep);
}

.nav-link.is-active {
  font-weight: 700;
}

.nav-link.is-active svg {
  color: var(--color-text);
}

.head-tools {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 8px;
}

.lang-control {
  position: relative;
}

.lang-button,
.menu-toggle {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 10px;
  border: 0;
  border-radius: var(--radius-sm);
  color: var(--color-muted);
  background: transparent;
}

.lang-button:hover,
.menu-toggle:hover {
  color: var(--color-text);
  background: var(--color-panel-deep);
}

.lang-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  z-index: 60;
  display: none;
  width: 180px;
  padding: 8px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-panel);
  box-shadow: var(--shadow-card);
}

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

.lang-menu a {
  display: flex;
  min-height: 42px;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  font-size: 14px;
}

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

.login-button {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  justify-content: center;
  padding: 8px 18px;
  border: 1.5px solid var(--color-text);
  border-radius: var(--radius-pill);
  font-size: 14px;
  font-weight: 700;
  white-space: nowrap;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.login-button:hover {
  color: var(--color-panel);
  background: var(--color-text);
}

.menu-toggle {
  display: none;
}

.mobile-drawer {
  display: none;
}

.site-footer {
  margin-top: 80px;
  border-top: 1px solid var(--color-border);
  background: var(--color-panel-deep);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr 0.75fr;
  gap: 42px;
  padding-top: 64px;
  padding-bottom: 42px;
}

.footer-brand p {
  max-width: 32em;
  margin-top: 16px;
  color: var(--color-muted);
  font-size: 14px;
}

.footer-title {
  margin-bottom: 14px;
  font-size: 14px;
  font-weight: 800;
}

.footer-links {
  display: grid;
  gap: 7px;
}

.footer-links a {
  display: inline-flex;
  min-height: 30px;
  align-items: center;
  color: var(--color-muted);
  font-size: 14px;
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding-top: 22px;
  padding-bottom: 28px;
  border-top: 1px solid var(--color-border);
  color: var(--color-muted);
  font-size: 13px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 18px;
}

.reveal {
  transition: opacity 650ms ease, transform 650ms ease;
}

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

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

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

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

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

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

.prose a:not(.btn) {
  color: var(--color-accent-dark);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.prose h2 {
  margin-top: 64px;
}

.prose h3 {
  margin-top: 36px;
}

.prose ol:not([class]),
.prose ul:not([class]) {
  padding-left: 1.4em;
}

.prose table {
  border-collapse: collapse;
}

@media (max-width: 1180px) {
  .main-nav {
    display: none;
  }

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

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

  .mobile-drawer {
    position: absolute;
    top: 100%;
    right: var(--gutter);
    left: var(--gutter);
    z-index: 55;
    max-height: calc(100dvh - var(--header-height));
    padding: 12px;
    overflow-y: auto;
    overscroll-behavior: contain;
    border: 1px solid var(--color-border);
    border-radius: 0 0 var(--radius-xl) var(--radius-xl);
    background: var(--color-panel);
    box-shadow: var(--shadow-card-hover);
  }

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

  .mobile-drawer a {
    display: flex;
    width: 100%;
    min-height: 46px;
    align-items: center;
    gap: 10px;
    padding: 10px 12px;
    border-radius: var(--radius-sm);
  }

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

  .mobile-drawer svg {
    width: 18px;
    height: 18px;
  }

  .drawer-languages {
    display: grid;
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid var(--color-border);
  }
}

@media (max-width: 768px) {
  :root {
    --gutter: 16px;
    --header-height: 60px;
    --anchor-offset: 118px;
  }

  h1 {
    font-size: clamp(28px, 9vw, 40px);
    letter-spacing: -0.015em;
  }

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

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

  .section-compact {
    padding-top: 42px;
    padding-bottom: 42px;
  }

  .head-row {
    gap: 8px;
  }

  .brand-local,
  .lang-button > span:first-child {
    display: none;
  }

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

  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 34px 22px;
    padding-top: 48px;
  }

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

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

@media (max-width: 640px) {
  .tilt,
  [data-tilt] {
    transform: none;
  }

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

  .btn {
    white-space: normal;
  }

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

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

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

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