:root {
  --color-bg: #F8FCFF;
  --color-panel: #EDF7FF;
  --color-panel-strong: #DCEEFF;
  --color-border: #A9C9ED;
  --color-accent: #0057F2;
  --color-accent-dark: #0B2E73;
  --color-text: #072A5A;
  --color-muted: #526F91;
  --color-success: #14866D;
  --color-warn: #F07A2A;
  --color-error: #C83D4A;
  --color-white: #FFFFFF;
  --color-transparent: transparent;
  --font-display: "Inter", "Noto Sans SC", "Noto Sans JP", "Noto Sans KR", system-ui, sans-serif;
  --font-body: "Inter", "Noto Sans SC", "Noto Sans JP", "Noto Sans KR", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Consolas, monospace;
  --radius-small: 10px;
  --radius-medium: 16px;
  --radius-large: 26px;
  --radius-pill: 999px;
  --border-standard: 2px;
  --border-strong: 4px;
  --page-width: 1320px;
  --reading-width: 768px;
  --header-height: 88px;
  --gutter: 32px;
  --section-space: 96px;
  --toc-offset: 96px;
  --transition-fast: 180ms ease;
  --transition-medium: 360ms ease;
}

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

html {
  min-width: 0;
  scroll-behavior: smooth;
  background: var(--color-bg);
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 0;
  min-height: 100vh;
  margin: 0;
  overflow-x: clip;
  color: var(--color-text);
  background: var(--color-bg);
  font-family: var(--font-body);
  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 {
  max-width: 100%;
  height: auto;
}

img,
svg {
  display: block;
}

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

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

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

button {
  cursor: pointer;
}

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

h1,
h2,
h3,
h4 {
  color: var(--color-accent-dark);
  font-family: var(--font-display);
  line-height: 1.15;
  text-wrap: balance;
}

h1 {
  margin-bottom: 24px;
  font-size: clamp(44px, 6vw, 72px);
  font-weight: 850;
  letter-spacing: -0.055em;
}

h2 {
  margin-bottom: 20px;
  font-size: clamp(30px, 4vw, 44px);
  font-weight: 820;
  letter-spacing: -0.035em;
}

h3 {
  margin-bottom: 14px;
  font-size: clamp(21px, 2.5vw, 28px);
  font-weight: 800;
  letter-spacing: -0.02em;
}

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

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

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

:not(pre) > code {
  padding: 2px 7px;
  border: var(--border-standard) solid var(--color-border);
  border-radius: var(--radius-small);
  overflow-wrap: anywhere;
  color: var(--color-accent-dark);
  background: var(--color-panel);
  font-size: 0.9em;
}

pre {
  max-width: 100%;
  padding: 20px;
  overflow-x: auto;
  border: var(--border-standard) solid var(--color-border);
  border-radius: var(--radius-medium);
  color: var(--color-white);
  background: var(--color-accent-dark);
  font-family: var(--font-mono);
  overscroll-behavior-inline: contain;
  -webkit-overflow-scrolling: touch;
}

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

table {
  border-collapse: collapse;
}

th,
td {
  padding: 14px 16px;
  border-bottom: var(--border-standard) solid var(--color-border);
  text-align: left;
}

th {
  color: var(--color-accent-dark);
  background: var(--color-panel);
  font-weight: 800;
}

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

.wrap {
  width: 100%;
  max-width: calc(var(--page-width) + (var(--gutter) * 2));
  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);
  overflow-x: clip;
}

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

.section-kicker {
  margin-bottom: 12px;
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.lead {
  max-width: 760px;
  color: var(--color-muted);
  font-size: clamp(17px, 2vw, 20px);
}

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

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

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  border: 0;
  white-space: nowrap;
}

.button {
  min-height: 55px;
  padding: 0 25px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  border: var(--border-strong) solid var(--color-accent-dark);
  border-radius: var(--radius-medium);
  font-size: 16px;
  font-weight: 800;
  line-height: 1.2;
  transition:
    color var(--transition-fast),
    background-color var(--transition-fast),
    transform var(--transition-fast);
}

.button-primary {
  color: var(--color-white);
  background: var(--color-accent);
}

.button-primary:hover,
.button-primary:focus-visible {
  color: var(--color-white);
  background: var(--color-warn);
  transform: translateY(-2px);
}

.button-secondary {
  color: var(--color-accent-dark);
  background: var(--color-white);
}

.button-secondary:hover,
.button-secondary:focus-visible {
  color: var(--color-accent);
  background: var(--color-panel);
  transform: translateY(-2px);
}

.button-quiet {
  min-height: 46px;
  border-width: var(--border-standard);
  color: var(--color-accent-dark);
  background: var(--color-panel);
}

.button[aria-disabled="true"],
.button:disabled {
  color: var(--color-muted);
  background: var(--color-panel-strong);
  cursor: not-allowed;
  transform: none;
}

.button-arrow {
  flex-shrink: 0;
  font-size: 20px;
  line-height: 1;
}

.badge,
.tag,
.eyebrow {
  width: fit-content;
  max-width: 100%;
  overflow: hidden;
  display: inline-flex;
  align-items: center;
  gap: 9px;
  border: var(--border-standard) solid var(--color-border);
  border-radius: var(--radius-pill);
  color: var(--color-accent-dark);
  background: var(--color-panel);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 750;
  letter-spacing: 0.03em;
}

.badge,
.tag {
  padding: 6px 11px;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.eyebrow {
  margin-bottom: 23px;
  padding: 9px 14px;
}

.badge-dot,
.eyebrow-dot,
.status-dot {
  width: 9px;
  height: 9px;
  flex: 0 0 auto;
  border: var(--border-standard) solid var(--color-accent-dark);
  border-radius: 50%;
  background: var(--color-warn);
}

.panel,
.card {
  border: var(--border-standard) solid var(--color-border);
  border-radius: var(--radius-large);
  background: var(--color-white);
}

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

.card {
  padding: 26px;
}

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

.site-header {
  position: relative;
  z-index: 50;
  height: var(--header-height);
  border-bottom: var(--border-standard) solid var(--color-panel-strong);
  background: var(--color-bg);
}

.header-inner {
  width: min(calc(100% - 64px), var(--page-width));
  height: 100%;
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: 30px;
}

.brand {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 11px;
}

.brand-mark {
  width: 40px;
  height: 40px;
  flex: 0 0 auto;
  overflow: hidden;
  border: var(--border-standard) solid var(--color-accent-dark);
  border-radius: var(--radius-small);
  background: var(--color-accent);
}

.brand-mark img {
  width: 100%;
  height: 100%;
}

.brand-copy {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  white-space: nowrap;
}

.brand-en {
  color: var(--color-text);
  font-size: 20px;
  font-weight: 800;
  letter-spacing: -0.03em;
}

.brand-zh {
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 600;
}

.main-nav {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 25px;
}

.main-nav a {
  position: relative;
  padding: 10px 0;
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 650;
  white-space: nowrap;
  transition: color var(--transition-fast), transform var(--transition-fast);
}

.main-nav a:hover,
.main-nav a:focus-visible {
  color: var(--color-accent);
  transform: translateY(-1px);
}

.main-nav a[aria-current="page"] {
  color: var(--color-text);
  font-weight: 800;
}

.main-nav a[aria-current="page"]::after {
  position: absolute;
  right: 0;
  bottom: 3px;
  left: 0;
  height: 3px;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
  content: "";
}

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

.login-link {
  min-height: 42px;
  padding: 0 19px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: var(--border-standard) solid var(--color-accent-dark);
  border-radius: var(--radius-pill);
  color: var(--color-accent-dark);
  background: var(--color-white);
  font-size: 14px;
  font-weight: 800;
  white-space: nowrap;
  transition:
    color var(--transition-fast),
    background-color var(--transition-fast),
    transform var(--transition-fast);
}

.login-link:hover,
.login-link:focus-visible {
  color: var(--color-white);
  background: var(--color-accent-dark);
  transform: translateY(-1px);
}

.language-menu {
  position: relative;
}

.language-button {
  min-width: 44px;
  min-height: 42px;
  padding: 0 8px;
  border: 0;
  color: var(--color-muted);
  background: var(--color-transparent);
  font-size: 13px;
  font-weight: 700;
  white-space: nowrap;
}

.language-list {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  z-index: 70;
  width: 170px;
  padding: 8px;
  display: none;
  border: var(--border-standard) solid var(--color-accent-dark);
  border-radius: var(--radius-medium);
  background: var(--color-white);
}

.language-menu.open .language-list {
  display: grid;
}

.language-list a {
  min-height: 42px;
  padding: 8px 11px;
  display: flex;
  align-items: center;
  border-radius: var(--radius-small);
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 700;
}

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

.menu-toggle {
  min-width: 44px;
  min-height: 44px;
  padding: 9px;
  display: none;
  border: var(--border-standard) solid var(--color-accent-dark);
  border-radius: var(--radius-small);
  background: var(--color-white);
}

.menu-toggle span {
  width: 21px;
  height: 2px;
  margin: 4px auto;
  display: block;
  border-radius: var(--radius-pill);
  background: var(--color-accent-dark);
}

.mobile-nav {
  position: absolute;
  top: 100%;
  right: 0;
  left: 0;
  z-index: 65;
  max-height: calc(100dvh - var(--header-height));
  padding: 10px var(--gutter) 20px;
  overflow-y: auto;
  overscroll-behavior: contain;
  display: none;
  border-bottom: var(--border-strong) solid var(--color-accent-dark);
  background: var(--color-white);
}

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

.mobile-nav a {
  width: 100%;
  min-height: 48px;
  padding: 12px 8px;
  display: flex;
  align-items: center;
  border-bottom: var(--border-standard) solid var(--color-panel-strong);
  color: var(--color-text);
  font-weight: 750;
}

.mobile-nav a[aria-current="page"] {
  color: var(--color-accent);
}

.mobile-languages {
  padding-top: 10px;
}

.mobile-languages strong {
  padding: 8px;
  display: block;
  color: var(--color-muted);
  font-size: 12px;
}

.nav-veil {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 40;
  display: none;
  border: 0;
  background: var(--color-accent-dark);
  opacity: 0.45;
}

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

.site-footer {
  border-top: var(--border-strong) solid var(--color-accent-dark);
  background: var(--color-panel-strong);
}

.footer-main {
  padding-top: 64px;
  padding-bottom: 48px;
  display: grid;
  grid-template-columns: minmax(260px, 1.25fr) repeat(3, minmax(160px, 1fr));
  gap: 42px;
}

.footer-brand p {
  max-width: 360px;
  margin-top: 18px;
}

.footer-title {
  margin-bottom: 15px;
  color: var(--color-accent-dark);
  font-size: 14px;
  font-weight: 850;
}

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

.footer-links a {
  width: fit-content;
  max-width: 100%;
  color: var(--color-muted);
  font-size: 14px;
}

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

.footer-bottom {
  padding-top: 20px;
  padding-bottom: 24px;
  display: flex;
  justify-content: space-between;
  gap: 20px;
  border-top: var(--border-standard) solid var(--color-border);
  color: var(--color-muted);
  font-size: 13px;
}

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

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

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

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

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

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

.prose p,
.prose li {
  overflow-wrap: break-word;
}

.prose blockquote {
  margin: 28px 0;
}

.prose ol.steps {
  padding: 0;
  list-style: none;
  counter-reset: steps;
}

.prose ol.steps > li {
  position: relative;
  min-height: 46px;
  padding-left: 54px;
  counter-increment: steps;
}

.prose ol.steps > li::before {
  position: absolute;
  top: 0;
  left: 0;
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border: var(--border-standard) solid var(--color-accent-dark);
  border-radius: 50%;
  color: var(--color-white);
  background: var(--color-accent);
  font-family: var(--font-mono);
  font-weight: 800;
  content: counter(steps);
}

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

.tilt,
.tilt-card {
  transform: rotate(-0.45deg);
}

@media (max-width: 1120px) {
  :root {
    --gutter: 24px;
  }

  .header-inner {
    width: 100%;
    padding-inline: var(--gutter);
    gap: 18px;
  }

  .main-nav {
    gap: 15px;
  }

  .main-nav a {
    font-size: 13px;
  }

  .language-button {
    font-size: 0;
  }

  .language-button::after {
    font-size: 13px;
    content: "语言 ▾";
  }
}

@media (max-width: 900px) {
  :root {
    --header-height: 72px;
    --section-space: 72px;
    --toc-offset: 82px;
  }

  .main-nav,
  .language-menu {
    display: none;
  }

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

  .menu-toggle {
    display: block;
  }

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

@media (max-width: 640px) {
  :root {
    --gutter: 18px;
    --section-space: 58px;
  }

  body {
    overflow-x: clip;
  }

  h1 {
    font-size: clamp(42px, 13vw, 58px);
  }

  h2 {
    font-size: 31px;
  }

  .wrap,
  .reading-wrap {
    width: 100%;
    padding-inline: var(--gutter);
  }

  .header-inner {
    padding-inline: var(--gutter);
  }

  .brand-copy {
    gap: 5px;
  }

  .brand-zh {
    display: none;
  }

  .login-link {
    min-height: 40px;
    padding-inline: 14px;
  }

  .header-tools {
    margin-left: auto;
    gap: 7px;
  }

  .button {
    width: 100%;
  }

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

  .footer-bottom {
    flex-direction: column;
  }

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

  pre,
  .table-scroll {
    max-width: 100%;
    overflow-x: auto;
  }
}

@media (max-width: 380px) {
  :root {
    --gutter: 16px;
  }

  .brand-mark {
    width: 36px;
    height: 36px;
  }

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

  .login-link {
    padding-inline: 11px;
    font-size: 13px;
  }
}

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

  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
  }

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