:root {
  --color-canvas: #FDF6ED;
  --color-surface: #FFFFFF;
  --color-surface-warm: #FFF9F2;
  --color-ink-dark: #2A1B12;
  --color-border: #EADDCC;
  --color-brand: #EF6C33;
  --color-brand-deep: #C8501C;
  --color-text: #2B2117;
  --color-text-muted: #7A6A5B;
  --color-positive: #3E9B63;
  --color-caution: #E0A11C;
  --color-negative: #D24B3F;
  --color-sunrise: #FFC89B;
  --color-rose: #F7AFB9;
  --color-violet: #8C68D8;
  --color-blue: #4386C7;
  --color-flag-red: #CC2E3C;
  --color-flag-blue: #31479E;
  --color-flag-green: #238553;
  --color-flag-yellow: #F2C94C;
  --color-transparent: transparent;
  --color-dark-text: #FDF6ED;
  --color-dark-muted: #C8B9AA;
  --color-dark-line: #58483D;
  --color-focus-shadow: #FFFFFF;

  --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", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --radius-xs: 6px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 22px;
  --radius-pill: 999px;

  --shadow-low: 0 2px 7px color-mix(in srgb, var(--color-text) 7%, var(--color-transparent));
  --shadow-card: 0 2px 6px color-mix(in srgb, var(--color-text) 6%, var(--color-transparent)), 0 26px 60px -18px color-mix(in srgb, var(--color-brand-deep) 26%, var(--color-transparent));
  --shadow-button: 0 8px 22px -6px color-mix(in srgb, var(--color-brand) 45%, var(--color-transparent));
  --shadow-float: 0 18px 45px -15px color-mix(in srgb, var(--color-ink-dark) 52%, var(--color-transparent));

  --content-width: 1264px;
  --reading-width: 800px;
  --header-height: 66px;
  --gutter: 32px;
  --section-space: clamp(72px, 9vw, 128px);
  --toc-offset: 82px;
  --transition-fast: 150ms ease;
  --transition-base: 260ms ease;
}

*,
*::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;
  min-height: 100%;
  margin: 0;
  overflow-x: clip;
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-canvas);
  -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;
}

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

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

button,
summary {
  color: inherit;
}

button {
  border: 0;
  cursor: pointer;
}

ul,
ol {
  margin: 0;
}

ul[role="list"],
.clean-list {
  padding: 0;
  list-style: none;
}

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

p:last-child {
  margin-bottom: 0;
}

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

h1,
.hero-title {
  margin-bottom: 18px;
  font-size: clamp(52px, 5.1vw, 72px);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(34px, 4vw, 52px);
  font-weight: 800;
  line-height: 1.16;
  letter-spacing: -0.018em;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2.2vw, 28px);
  font-weight: 750;
  line-height: 1.28;
}

h4 {
  margin-bottom: 10px;
  font-size: 18px;
  font-weight: 750;
}

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

code {
  overflow-wrap: anywhere;
}

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

::selection {
  color: var(--color-surface);
  background: var(--color-brand-deep);
}

:where(a, button, input, select, textarea, summary, [role="tab"]):focus-visible {
  outline: 2px solid var(--color-brand);
  outline-offset: 3px;
}

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

.text-gradient,
.grad {
  color: var(--color-brand);
  background: linear-gradient(118deg, var(--color-brand) 12%, var(--color-brand-deep) 88%);
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: var(--color-transparent);
}

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

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

.wrap {
  width: 100%;
  max-width: var(--content-width);
  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);
}

.section-tight {
  padding-top: clamp(48px, 6vw, 76px);
  padding-bottom: clamp(48px, 6vw, 76px);
}

.section-head {
  max-width: 760px;
  margin-bottom: clamp(30px, 5vw, 54px);
}

.section-head > p {
  max-width: 680px;
  margin-bottom: 0;
  font-size: 17px;
  color: var(--color-text-muted);
}

.dark-section {
  position: relative;
  overflow-x: clip;
  color: var(--color-dark-text);
  background: var(--color-ink-dark);
}

.dark-section::before {
  position: absolute;
  inset: 0;
  pointer-events: none;
  content: "";
  background-image:
    radial-gradient(color-mix(in srgb, var(--color-surface) 7%, var(--color-transparent)) 1px, var(--color-transparent) 1.4px),
    radial-gradient(color-mix(in srgb, var(--color-surface) 4%, var(--color-transparent)) 1px, var(--color-transparent) 1.4px);
  background-position: 0 0, 4px 6px;
  background-size: 9px 9px, 13px 13px;
}

.dark-section > * {
  position: relative;
}

.dark-section h1,
.dark-section h2,
.dark-section h3,
.dark-section h4 {
  color: var(--color-dark-text);
}

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

.eyebrow,
.badge {
  display: inline-flex;
  align-items: center;
  max-width: 100%;
  min-height: 30px;
  gap: 8px;
  padding: 5px 13px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  color: var(--color-text-muted);
  background: var(--color-surface);
  font-size: 13px;
  line-height: 1.35;
  overflow-wrap: anywhere;
}

.eyebrow-dot,
.status-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: var(--radius-pill);
  background: var(--color-brand);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-brand) 18%, var(--color-transparent));
}

.status-dot.is-good {
  background: var(--color-positive);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-positive) 18%, var(--color-transparent));
}

.status-dot.is-warn {
  background: var(--color-caution);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-caution) 18%, var(--color-transparent));
}

.badge-accent {
  border-color: color-mix(in srgb, var(--color-brand) 42%, var(--color-border));
  color: var(--color-brand-deep);
  background: color-mix(in srgb, var(--color-brand) 8%, var(--color-surface));
}

.btn,
.btn-main,
.btn-sub,
.btn-login {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 24px;
  min-height: 44px;
  gap: 8px;
  padding-inline: 24px;
  border-radius: var(--radius-md);
  font-weight: 700;
  line-height: 1;
  text-align: center;
  transition: transform var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast), background var(--transition-fast), box-shadow var(--transition-fast);
}

.btn:hover,
.btn-main:hover,
.btn-sub:hover,
.btn-login:hover {
  transform: translateY(-1px);
}

.btn-primary,
.btn-main {
  border: 1px solid var(--color-brand);
  color: var(--color-surface);
  background: linear-gradient(180deg, var(--color-brand), var(--color-brand-deep));
  box-shadow: var(--shadow-button);
}

.btn-secondary,
.btn-sub {
  border: 1px solid color-mix(in srgb, var(--color-text) 24%, var(--color-border));
  color: var(--color-text);
  background: var(--color-transparent);
}

.btn-secondary:hover,
.btn-sub:hover {
  border-color: var(--color-brand);
  color: var(--color-brand-deep);
  background: var(--color-surface);
}

.btn-quiet {
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  background: var(--color-surface);
}

.btn[aria-disabled="true"],
.btn:disabled {
  cursor: not-allowed;
  opacity: 0.55;
  transform: none;
  box-shadow: none;
}

.btn-sm {
  min-height: 38px;
  padding-inline: 17px;
  font-size: 14px;
}

.btn-lg,
.btn-main,
.btn-sub {
  min-height: 50px;
  padding-inline: 28px;
  font-size: 16px;
}

.icon-inline {
  width: 16px;
  height: 16px;
  flex: 0 0 auto;
}

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

.card {
  padding: 24px;
}

.site-head {
  position: relative;
  z-index: 80;
  border-bottom: 1px solid color-mix(in srgb, var(--color-border) 65%, var(--color-transparent));
  background: color-mix(in srgb, var(--color-canvas) 92%, var(--color-surface));
}

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

.brand {
  display: inline-flex;
  min-height: 44px;
  flex: 0 0 auto;
  align-items: center;
  gap: 9px;
}

.brand-logo {
  width: 25px;
  height: 25px;
}

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

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

.desktop-tabs {
  display: flex;
  height: var(--header-height);
  align-items: stretch;
  gap: 2px;
  margin-left: auto;
}

.desktop-tabs a {
  position: relative;
  display: flex;
  min-height: 44px;
  align-items: center;
  padding-inline: 11px;
  color: var(--color-text-muted);
  font-size: 13.5px;
  transition: color var(--transition-fast);
}

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

.desktop-tabs a.is-active {
  font-weight: 700;
}

.desktop-tabs a.is-active::after {
  position: absolute;
  right: 11px;
  bottom: -1px;
  left: 11px;
  height: 2px;
  border-radius: var(--radius-xs) var(--radius-xs) 0 0;
  content: "";
  background: var(--color-brand);
}

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

.language-box {
  position: relative;
}

.language-toggle {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 5px;
  padding-inline: 8px;
  color: var(--color-text-muted);
  background: var(--color-transparent);
  font-size: 13px;
}

.language-menu {
  position: absolute;
  top: calc(100% + 7px);
  right: 0;
  z-index: 95;
  display: none;
  width: 172px;
  padding: 7px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  box-shadow: var(--shadow-card);
}

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

.language-menu a {
  display: flex;
  min-height: 40px;
  align-items: center;
  padding-inline: 11px;
  border-radius: var(--radius-xs);
  color: var(--color-text-muted);
  font-size: 14px;
}

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

.btn-login {
  min-height: 36px;
  padding-inline: 18px;
  border: 1px solid color-mix(in srgb, var(--color-brand) 55%, var(--color-border));
  border-radius: var(--radius-pill);
  color: var(--color-brand-deep);
  background: var(--color-surface);
  font-size: 14px;
}

.btn-login:hover {
  border-color: var(--color-brand);
  color: var(--color-surface);
  background: var(--color-brand);
}

.menu-toggle {
  display: none;
  width: 44px;
  min-width: 44px;
  min-height: 44px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
  border-radius: var(--radius-sm);
  background: var(--color-transparent);
}

.menu-toggle span {
  width: 20px;
  height: 2px;
  border-radius: var(--radius-pill);
  background: var(--color-text);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.menu-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.menu-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.menu-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.mobile-nav {
  position: absolute;
  top: 100%;
  right: 0;
  left: 0;
  z-index: 92;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  overflow-y: auto;
  overscroll-behavior: contain;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface);
  box-shadow: var(--shadow-card);
}

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

.mobile-nav-inner {
  padding-top: 10px;
  padding-bottom: 16px;
}

.mobile-nav a {
  display: flex;
  width: 100%;
  min-height: 46px;
  align-items: center;
  padding: 10px 14px;
  border-radius: var(--radius-xs);
  color: var(--color-text-muted);
}

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

.mobile-language {
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid var(--color-border);
}

.mobile-language-label {
  padding: 8px 14px 4px;
  color: var(--color-text-muted);
  font-size: 12px;
  letter-spacing: 0.08em;
}

.site-footer {
  position: relative;
  overflow-x: clip;
  border-top: 1px solid var(--color-dark-line);
  color: var(--color-dark-muted);
  background: var(--color-ink-dark);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.3fr 1fr 1fr 0.8fr;
  gap: 48px;
  padding-top: 68px;
  padding-bottom: 48px;
}

.footer-brand .brand-name,
.site-footer h3 {
  color: var(--color-dark-text);
}

.footer-brand p {
  max-width: 330px;
  margin-top: 16px;
  color: var(--color-dark-muted);
}

.footer-heading {
  margin-bottom: 14px;
  color: var(--color-dark-text);
  font-size: 14px;
  letter-spacing: 0.05em;
}

.footer-links {
  padding: 0;
  list-style: none;
}

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

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

.footer-legal {
  display: flex;
  min-height: 68px;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 22px;
  border-top: 1px solid var(--color-dark-line);
  font-size: 13px;
}

.footer-legal p {
  margin: 0 auto 0 0;
}

.footer-legal a:hover {
  color: var(--color-dark-text);
}

.prose {
  font-size: 16px;
}

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

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

.prose h2 {
  margin-top: 2.2em;
}

.prose h3 {
  margin-top: 1.8em;
}

.prose a:not(.btn) {
  color: var(--color-brand-deep);
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--color-brand) 45%, var(--color-transparent));
  text-underline-offset: 3px;
}

.prose table {
  border-collapse: collapse;
}

.reveal {
  transition: opacity 560ms ease, transform 560ms ease;
}

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

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

body:has(.toc-tabs) section[id] {
  scroll-margin-top: calc(var(--toc-offset) + 56px);
}

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

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

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

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

@media (max-width: 768px) {
  :root {
    --gutter: 20px;
    --header-height: 62px;
  }

  h1,
  .hero-title {
    font-size: clamp(32px, 9.4vw, 40px);
    line-height: 1.12;
  }

  h2 {
    font-size: clamp(28px, 7.4vw, 38px);
  }

  .language-box {
    display: none;
  }

  .head-row {
    gap: 10px;
  }

  .brand-local {
    display: none;
  }

  .btn-login {
    min-width: 64px;
    padding-inline: 14px;
  }

  .footer-grid {
    gap: 34px 24px;
  }
}

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

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

  body {
    font-size: 14.5px;
  }

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

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

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

  .cta-row {
    align-items: stretch;
  }

  .cta-row .btn,
  .cta-row .btn-main,
  .cta-row .btn-sub {
    width: 100%;
  }

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

  .footer-legal {
    align-items: flex-start;
    padding-top: 22px;
    padding-bottom: 22px;
  }

  .footer-legal p {
    width: 100%;
  }
}

@media (max-width: 390px) {
  .brand-name {
    font-size: 17px;
  }

  .btn-login {
    min-width: 58px;
    padding-inline: 11px;
  }

  .head-row {
    gap: 6px;
  }
}

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

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

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