:root {
  --color-bg: #F4F6F1;
  --color-panel: #FCFDF9;
  --color-panel-alt: #EAF1F0;
  --color-border: #CED9D8;
  --color-accent: #258FCB;
  --color-accent-dark: #176F9D;
  --color-text: #243137;
  --color-muted: #66777C;
  --color-success: #46B9A9;
  --color-warn: #F26B5B;
  --color-error: #C94B45;
  --color-white-glass: rgba(252, 253, 249, 0.78);
  --color-white-strong: rgba(252, 253, 249, 0.94);
  --color-cyan-glass: rgba(234, 241, 240, 0.76);
  --color-cyan-soft: rgba(70, 185, 169, 0.12);
  --color-blue-soft: rgba(37, 143, 203, 0.11);
  --color-warn-soft: rgba(242, 107, 91, 0.12);
  --color-warn-line: rgba(242, 107, 91, 0.38);
  --color-error-soft: rgba(201, 75, 69, 0.1);
  --color-border-glass: rgba(206, 217, 216, 0.82);
  --color-border-soft: rgba(206, 217, 216, 0.54);
  --color-text-soft: rgba(36, 49, 55, 0.08);
  --color-grid: rgba(37, 143, 203, 0.055);
  --color-sky-glow: rgba(37, 143, 203, 0.16);
  --color-mint-glow: rgba(70, 185, 169, 0.13);
  --color-cream-glow: rgba(252, 253, 249, 0.86);
  --color-black-glass: rgba(36, 49, 55, 0.16);
  --color-overlay: rgba(36, 49, 55, 0.38);
  --color-footer: #243137;
  --color-footer-panel: #2E3D43;
  --color-footer-text: #EAF1F0;
  --color-footer-muted: #AFBFBE;
  --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-xs: 7px;
  --radius-sm: 11px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  --radius-pill: 999px;
  --page-max: 1320px;
  --content-max: 860px;
  --header-height: 84px;
  --gutter: clamp(16px, 4vw, 36px);
  --section-space: clamp(72px, 9vw, 124px);
  --toc-offset: 96px;
  --ease-out: cubic-bezier(0.2, 0.75, 0.25, 1);
  --transition-fast: 180ms var(--ease-out);
  --transition-slow: 620ms var(--ease-out);
}

*,
*::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:
    radial-gradient(circle at 82% 16%, var(--color-sky-glow), transparent 28%),
    radial-gradient(circle at 68% 58%, var(--color-mint-glow), transparent 31%),
    linear-gradient(128deg, var(--color-bg) 0%, var(--color-cream-glow) 45%, var(--color-panel-alt) 100%);
  font-family: var(--font-body);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body::before {
  position: fixed;
  inset: 0;
  z-index: -1;
  content: "";
  pointer-events: none;
  opacity: 0.72;
  background-image:
    linear-gradient(var(--color-grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-grid) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: linear-gradient(to bottom, transparent, var(--color-text) 22%, transparent 88%);
}

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

img {
  height: auto;
}

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

button,
summary {
  -webkit-tap-highlight-color: transparent;
}

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

p,
ul,
ol,
dl,
blockquote,
pre,
table {
  margin-top: 0;
}

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

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

code {
  overflow-wrap: anywhere;
}

pre {
  max-width: 100%;
  padding: 18px;
  overflow-x: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-footer);
  color: var(--color-footer-text);
  line-height: 1.65;
  -webkit-overflow-scrolling: touch;
}

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

table {
  border-collapse: collapse;
}

th,
td {
  padding: 13px 15px;
  border-bottom: 1px solid var(--color-border-soft);
  text-align: left;
}

th {
  color: var(--color-text);
  background: var(--color-panel-alt);
  font-size: 0.84rem;
}

:focus-visible {
  outline: 3px solid var(--color-sky-glow);
  outline-offset: 3px;
}

::selection {
  color: var(--color-text);
  background: var(--color-cyan-soft);
}

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

.content-wrap {
  width: 100%;
  max-width: calc(var(--content-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: clamp(48px, 6vw, 78px);
  padding-bottom: clamp(48px, 6vw, 78px);
}

section,
.hero,
.preview-section,
.site-footer {
  position: relative;
  overflow-x: clip;
}

.grid,
.flex,
[class*="grid"],
[class*="layout"],
[class*="columns"] {
  min-width: 0;
}

h1,
h2,
h3,
h4 {
  color: var(--color-text);
  font-family: var(--font-display);
  line-height: 1.16;
  text-wrap: balance;
}

h1 {
  margin: 0;
  font-size: clamp(3.3rem, 5.2vw, 4.7rem);
  font-weight: 780;
  letter-spacing: -0.055em;
}

h2 {
  margin: 0 0 18px;
  font-size: clamp(2rem, 3.3vw, 3.25rem);
  font-weight: 750;
  letter-spacing: -0.04em;
}

h3 {
  margin: 0 0 12px;
  font-size: clamp(1.25rem, 2vw, 1.65rem);
  font-weight: 720;
  letter-spacing: -0.025em;
}

h4 {
  margin: 0 0 10px;
  font-size: 1rem;
}

.lead {
  max-width: 720px;
  color: var(--color-muted);
  font-size: clamp(1.04rem, 1.5vw, 1.2rem);
}

.kicker,
.eyebrow {
  width: max-content;
  max-width: 100%;
  margin: 0 0 19px;
  padding: 8px 12px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  display: inline-flex;
  align-items: center;
  gap: 9px;
  overflow: hidden;
  background: var(--color-white-glass);
  color: var(--color-accent-dark);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 650;
  letter-spacing: 0.06em;
}

.eyebrow-dot,
.status-dot,
.badge-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: var(--radius-pill);
  background: var(--color-success);
}

.title-accent {
  color: var(--color-accent);
  background: linear-gradient(104deg, var(--color-accent-dark), var(--color-accent), var(--color-success));
  background-clip: text;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

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

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

.panel,
.card {
  min-width: 0;
  border: 1px solid var(--color-border-glass);
  border-radius: var(--radius-lg);
  background: var(--color-white-glass);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.panel {
  padding: clamp(22px, 3vw, 36px);
}

.card {
  padding: 24px;
}

.button,
.cta {
  min-height: 48px;
  padding: 0 22px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  font-size: 0.92rem;
  font-weight: 720;
  line-height: 1;
  cursor: pointer;
  transition:
    transform var(--transition-fast),
    background-color var(--transition-fast),
    border-color var(--transition-fast),
    color var(--transition-fast);
}

.button:hover,
.button:focus-visible,
.cta:hover,
.cta:focus-visible {
  transform: translateY(-2px);
}

.button-primary,
.cta-primary {
  border-color: var(--color-warn);
  background: var(--color-warn);
  color: var(--color-panel);
}

.button-secondary,
.cta-secondary {
  border-color: var(--color-border);
  background: var(--color-white-strong);
  color: var(--color-text);
}

.button-secondary:hover,
.button-secondary:focus-visible,
.cta-secondary:hover,
.cta-secondary:focus-visible {
  border-color: var(--color-accent);
  background: var(--color-blue-soft);
}

.button-quiet {
  border-color: var(--color-border);
  background: transparent;
  color: var(--color-accent-dark);
}

.button[disabled],
.button.is-disabled {
  opacity: 0.48;
  pointer-events: none;
}

.button-icon,
.cta-arrow {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}

.badge,
.tag,
.chip {
  max-width: 100%;
  min-height: 28px;
  padding: 5px 10px;
  border: 1px solid var(--color-border-soft);
  border-radius: var(--radius-pill);
  display: inline-flex;
  align-items: center;
  gap: 7px;
  overflow: hidden;
  color: var(--color-muted);
  background: var(--color-panel);
  font-size: 0.75rem;
  font-weight: 650;
  line-height: 1.2;
  text-overflow: ellipsis;
  white-space: nowrap;
}

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

.badge-warn {
  border-color: var(--color-warn-line);
  color: var(--color-warn);
  background: var(--color-warn-soft);
}

.site-header {
  position: relative;
  z-index: 50;
  height: var(--header-height);
  border-bottom: 1px solid var(--color-border-soft);
  background: var(--color-white-glass);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
}

.header-inner {
  width: 100%;
  max-width: calc(var(--page-max) + (var(--gutter) * 2));
  height: 100%;
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 24px;
}

.brand {
  min-width: 176px;
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 11px;
}

.brand-mark {
  width: 38px;
  height: 38px;
  flex: 0 0 auto;
}

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

.brand-en {
  font-family: var(--font-display);
  font-size: 1.12rem;
  font-weight: 760;
  letter-spacing: -0.025em;
}

.brand-cn {
  color: var(--color-muted);
  font-size: 0.74rem;
  font-weight: 520;
}

.primary-nav {
  min-width: 0;
  margin-left: auto;
  display: flex;
  align-items: center;
  white-space: nowrap;
}

.nav-link {
  position: relative;
  padding: 9px 6px;
  color: var(--color-muted);
  font-size: 0.79rem;
  font-weight: 560;
  transition: color var(--transition-fast);
}

.nav-link:not(:last-child)::after {
  margin-left: 12px;
  color: var(--color-border);
  content: "·";
}

.nav-link:hover,
.nav-link:focus-visible,
.nav-link[aria-current="page"] {
  color: var(--color-accent-dark);
}

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

.login-button,
.language-button,
.menu-button {
  min-height: 40px;
  border-radius: var(--radius-pill);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  white-space: nowrap;
}

.login-button {
  padding: 0 17px;
  border: 1px solid var(--color-accent);
  color: var(--color-accent-dark);
  background: var(--color-white-strong);
  font-size: 0.8rem;
  font-weight: 680;
  transition:
    transform var(--transition-fast),
    background-color var(--transition-fast);
}

.login-button:hover,
.login-button:focus-visible {
  transform: translateY(-1px);
  background: var(--color-blue-soft);
}

.language-menu {
  position: relative;
}

.language-button {
  padding: 0 12px;
  border: 1px solid var(--color-border);
  background: var(--color-white-glass);
  color: var(--color-muted);
  font-size: 0.74rem;
  cursor: pointer;
}

.language-popover {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  z-index: 65;
  width: 174px;
  padding: 7px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  display: none;
  background: var(--color-panel);
}

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

.language-popover a {
  min-height: 40px;
  padding: 8px 11px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  color: var(--color-muted);
  font-size: 0.8rem;
}

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

.menu-button {
  display: none;
  min-width: 44px;
  min-height: 44px;
  padding: 0;
  border: 1px solid var(--color-border);
  background: var(--color-panel);
  cursor: pointer;
}

.menu-button-lines {
  width: 18px;
  display: grid;
  gap: 4px;
}

.menu-button-lines i {
  width: 100%;
  height: 2px;
  border-radius: var(--radius-pill);
  display: block;
  background: var(--color-text);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.menu-button[aria-expanded="true"] .menu-button-lines i:first-child {
  transform: translateY(6px) rotate(45deg);
}

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

.menu-button[aria-expanded="true"] .menu-button-lines i:last-child {
  transform: translateY(-6px) rotate(-45deg);
}

.mobile-nav {
  position: absolute;
  top: var(--header-height);
  right: 0;
  left: 0;
  z-index: 64;
  max-height: calc(100dvh - var(--header-height));
  padding: 10px var(--gutter) 20px;
  overflow-y: auto;
  overscroll-behavior: contain;
  border-bottom: 1px solid var(--color-border);
  display: none;
  background: var(--color-panel);
}

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

.mobile-nav a {
  width: 100%;
  min-height: 48px;
  padding: 12px 8px;
  border-bottom: 1px solid var(--color-border-soft);
  display: flex;
  align-items: center;
  color: var(--color-muted);
  font-weight: 650;
}

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

.mobile-language-title {
  margin: 18px 8px 4px;
  color: var(--color-muted);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
}

.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;
}

.hero {
  min-height: 746px;
}

.hero-grid {
  min-height: 746px;
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  align-items: center;
  gap: 42px;
}

.hero-copy {
  position: relative;
  z-index: 2;
  min-width: 0;
  padding-bottom: 26px;
}

.hero-copy h1 {
  max-width: 640px;
}

.hero-description {
  max-width: 560px;
  margin: 24px 0 0;
  color: var(--color-muted);
  font-size: 1rem;
  line-height: 1.78;
}

.hero-description strong {
  color: var(--color-text);
}

.hero-actions {
  margin-top: 28px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}

.trust-line {
  margin: 24px 0 0;
  padding-top: 18px;
  border-top: 1px solid var(--color-border-soft);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  color: var(--color-muted);
  font-size: 0.72rem;
  font-weight: 580;
}

.trust-line span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.trust-line span:not(:last-child)::after {
  margin-left: 3px;
  color: var(--color-border);
  content: "·";
}

.trust-check {
  width: 14px;
  height: 14px;
  flex: 0 0 auto;
  fill: none;
  stroke: var(--color-success);
  stroke-width: 1.9;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.site-footer {
  margin-top: var(--section-space);
  color: var(--color-footer-text);
  background: var(--color-footer);
}

.footer-main {
  padding-top: 64px;
  padding-bottom: 52px;
  display: grid;
  grid-template-columns: minmax(230px, 1.3fr) repeat(3, minmax(150px, 1fr));
  gap: 48px;
}

.footer-brand {
  max-width: 340px;
}

.footer-brand .brand-en {
  color: var(--color-footer-text);
}

.footer-brand p {
  margin: 18px 0 0;
  color: var(--color-footer-muted);
  font-size: 0.88rem;
}

.footer-heading {
  margin: 0 0 14px;
  color: var(--color-footer-text);
  font-size: 0.82rem;
  letter-spacing: 0.04em;
}

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

.footer-links a {
  width: fit-content;
  color: var(--color-footer-muted);
  font-size: 0.82rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover,
.footer-links a:focus-visible {
  color: var(--color-footer-text);
}

.footer-bottom {
  padding-top: 20px;
  padding-bottom: 24px;
  border-top: 1px solid var(--color-footer-panel);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 14px;
  color: var(--color-footer-muted);
  font-size: 0.75rem;
}

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

.prose {
  color: var(--color-text);
  font-size: 1rem;
}

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

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

.prose h2 {
  margin-top: 2.6em;
}

.prose h3 {
  margin-top: 2em;
}

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

.prose a {
  color: var(--color-accent-dark);
  text-decoration: underline;
  text-decoration-color: var(--color-border);
  text-underline-offset: 3px;
}

.prose blockquote {
  margin-inline: 0;
}

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

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

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

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

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

.tilt,
.decorative-tilt {
  transform: rotate(-1deg);
}

@keyframes window-in {
  from {
    opacity: 0;
    transform: translateY(18px) scale(0.985);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes detail-in {
  from {
    opacity: 0;
    transform: translateY(-7px) scaleY(0.94);
  }
  to {
    opacity: 1;
    transform: none;
  }
}

@keyframes status-pulse {
  50% {
    opacity: 0.45;
    transform: scale(0.78);
  }
}

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

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

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

  .hero-grid {
    grid-template-columns: minmax(0, 0.88fr) minmax(0, 1.12fr);
    gap: 24px;
  }

  .footer-main {
    grid-template-columns: 1.2fr repeat(2, 1fr);
  }
}

@media (max-width: 900px) {
  :root {
    --header-height: 72px;
    --toc-offset: 84px;
  }

  .hero {
    min-height: auto;
    padding-top: 58px;
    padding-bottom: 76px;
  }

  .hero-grid {
    min-height: 0;
    grid-template-columns: minmax(0, 1fr);
  }

  .hero-copy {
    padding-bottom: 0;
  }

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

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

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
    --radius-xl: 24px;
    --section-space: 72px;
  }

  body::before {
    background-size: 36px 36px;
  }

  h1 {
    font-size: clamp(2.65rem, 13.5vw, 3.55rem);
    letter-spacing: -0.048em;
  }

  h2 {
    font-size: clamp(1.8rem, 9vw, 2.5rem);
  }

  .brand {
    min-width: 0;
  }

  .brand-mark {
    width: 34px;
    height: 34px;
  }

  .brand-en {
    font-size: 1rem;
  }

  .brand-cn,
  .header-tools > .language-menu {
    display: none;
  }

  .header-inner {
    gap: 8px;
  }

  .header-tools {
    margin-left: auto;
    gap: 6px;
  }

  .login-button {
    min-height: 40px;
    padding-inline: 13px;
  }

  .hero {
    padding-top: 42px;
    padding-bottom: 62px;
  }

  .hero-description {
    margin-top: 20px;
    font-size: 0.94rem;
  }

  .hero-actions {
    margin-top: 23px;
  }

  .hero-actions .cta,
  .hero-actions .button {
    flex: 1 1 140px;
  }

  .trust-line {
    align-items: flex-start;
  }

  .trust-line span {
    flex: 1 1 135px;
  }

  .trust-line span::after {
    display: none;
  }

  .panel,
  .card {
    padding: 20px;
  }

  .footer-main {
    grid-template-columns: minmax(0, 1fr);
    gap: 34px;
  }

  .footer-brand {
    grid-column: auto;
  }

  .footer-bottom {
    display: grid;
  }

  .tilt,
  .decorative-tilt {
    transform: none;
  }

  table {
    font-size: 0.86rem;
  }
}

@media (max-width: 380px) {
  .login-button {
    padding-inline: 11px;
    font-size: 0.75rem;
  }

  .brand-copy {
    display: none;
  }
}

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

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

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