:root {
  --color-page: #FFFFFF;
  --color-panel: #F7F7F5;
  --color-panel-strong: #EFEFEB;
  --color-border: #D9D9D4;
  --color-accent: #FF8500;
  --color-accent-dark: #C95400;
  --color-accent-soft: #FFF0DE;
  --color-accent-pale: #FFF8F0;
  --color-text: #171714;
  --color-muted: #686863;
  --color-success: #237A4B;
  --color-warning: #A85D00;
  --color-error: #B83A32;
  --color-white: #FFFFFF;
  --color-overlay: rgba(23, 23, 20, 0.42);
  --color-shadow: rgba(23, 23, 20, 0.10);
  --color-button-shadow: rgba(201, 84, 0, 0.16);
  --color-flag-blue: #234A86;
  --color-flag-dark-blue: #173A68;
  --color-flag-soft-blue: #3B65A2;
  --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;
  --layout-max: 1392px;
  --reading-max: 768px;
  --gutter: clamp(16px, 3.2vw, 32px);
  --header-height: 84px;
  --radius-xs: 8px;
  --radius-sm: 12px;
  --radius-button: 15px;
  --radius-card: 20px;
  --radius-hero: 32px;
  --radius-pill: 999px;
  --shadow-bubble: 0 18px 45px var(--color-shadow);
  --shadow-button: 0 8px 18px var(--color-button-shadow);
  --transition-fast: 180ms ease;
  --transition-reveal: 620ms cubic-bezier(0.22, 1, 0.36, 1);
  --toc-top: 92px;
  --toc-height: 58px;
  --section-space: clamp(72px, 9vw, 132px);
}

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

html {
  min-width: 320px;
  scroll-behavior: smooth;
  background: var(--color-page);
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  overflow-x: clip;
  background: var(--color-page);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  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;
}

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

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

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

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

p:last-child,
ul:last-child,
ol:last-child,
blockquote:last-child {
  margin-bottom: 0;
}

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

:not(pre) > code {
  padding: 0.12em 0.38em;
  border-radius: var(--radius-xs);
  background: var(--color-panel-strong);
  overflow-wrap: anywhere;
}

pre {
  max-width: 100%;
  overflow-x: auto;
  padding: 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-text);
  color: var(--color-white);
  -webkit-overflow-scrolling: touch;
}

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

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

h1,
.hero-title {
  font-size: clamp(52px, 5vw, 72px);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(34px, 4vw, 52px);
  font-weight: 850;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

h3 {
  font-size: clamp(23px, 2.5vw, 32px);
  font-weight: 800;
  line-height: 1.25;
}

h4 {
  font-size: 19px;
  font-weight: 800;
  line-height: 1.35;
}

.nowrap-term {
  white-space: nowrap;
}

.wrap {
  width: 100%;
  max-width: calc(var(--layout-max) + (var(--gutter) * 2));
  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: clamp(44px, 6vw, 76px);
  padding-bottom: clamp(44px, 6vw, 76px);
}

.panel {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  background: var(--color-panel);
}

.card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  background: var(--color-white);
}

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

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

.eyebrow {
  display: inline-flex;
  min-height: 32px;
  max-width: 100%;
  align-items: center;
  gap: 9px;
  padding: 4px 13px 4px 8px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-white);
  color: var(--color-text);
  font-size: 13px;
  font-weight: 700;
}

.eyebrow-dot,
.status-dot {
  flex: 0 0 auto;
  width: 9px;
  height: 9px;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
}

.badge {
  display: inline-flex;
  max-width: 100%;
  min-height: 30px;
  align-items: center;
  gap: 7px;
  padding: 4px 11px;
  overflow: hidden;
  border-radius: var(--radius-pill);
  background: var(--color-accent-soft);
  color: var(--color-accent-dark);
  font-size: 12px;
  font-weight: 750;
  line-height: 1.35;
}

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

.button,
.primary-cta,
.secondary-cta,
.login-button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 0 20px;
  border: 1px solid transparent;
  border-radius: var(--radius-button);
  cursor: pointer;
  font-weight: 780;
  line-height: 1.2;
  transition: transform var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast);
}

.button:hover,
.primary-cta:hover,
.secondary-cta:hover,
.login-button:hover {
  transform: translateY(-2px);
}

.button:focus-visible,
.primary-cta:focus-visible,
.secondary-cta:focus-visible,
.login-button:focus-visible,
.nav-link:focus-visible,
.language-trigger:focus-visible,
.menu-toggle:focus-visible {
  outline: 3px solid var(--color-accent-soft);
  outline-offset: 3px;
}

.button-primary,
.primary-cta {
  background: var(--color-accent);
  color: var(--color-text);
  box-shadow: var(--shadow-button);
}

.button-primary:hover,
.primary-cta:hover {
  background: var(--color-accent-dark);
  color: var(--color-white);
}

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

.button-secondary:hover,
.secondary-cta:hover {
  background: var(--color-panel);
}

.button-quiet {
  border-color: var(--color-text);
  background: var(--color-white);
}

.button[disabled],
.button.is-disabled {
  cursor: not-allowed;
  opacity: 0.48;
  transform: none;
}

.site-header {
  position: relative;
  z-index: 100;
  height: var(--header-height);
  border-bottom: 1px solid var(--color-border);
  background: var(--color-page);
}

.header-inner {
  width: 100%;
  max-width: calc(var(--layout-max) + (var(--gutter) * 2));
  height: 100%;
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 20px;
}

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

.brand-mark {
  width: 42px;
  height: 42px;
  flex: 0 0 42px;
}

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

.brand-en {
  font-size: 20px;
  font-weight: 850;
  letter-spacing: -0.02em;
}

.brand-cn {
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 600;
}

.main-nav {
  min-width: 0;
  height: 100%;
  flex: 1 1 auto;
  display: flex;
  align-items: stretch;
  justify-content: center;
  gap: 1px;
}

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  padding-inline: 9px;
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 650;
  white-space: nowrap;
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-text);
}

.nav-link.active::after {
  position: absolute;
  right: 9px;
  bottom: 0;
  left: 9px;
  height: 3px;
  border-radius: var(--radius-pill) var(--radius-pill) 0 0;
  background: var(--color-accent);
  content: "";
}

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

.language-picker {
  position: relative;
}

.language-trigger {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  gap: 7px;
  padding-inline: 10px;
  border: 0;
  background: transparent;
  color: var(--color-muted);
  cursor: pointer;
  font-size: 13px;
  font-weight: 650;
}

.language-trigger svg {
  width: 17px;
  height: 17px;
  flex: 0 0 auto;
}

.language-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  width: 170px;
  padding: 7px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-white);
  box-shadow: var(--shadow-bubble);
}

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

.language-menu a {
  display: flex;
  min-height: 42px;
  align-items: center;
  padding-inline: 12px;
  border-radius: var(--radius-xs);
  font-size: 13px;
  font-weight: 650;
}

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

.login-button {
  min-height: 42px;
  padding-inline: 18px;
  border-color: var(--color-text);
  background: var(--color-white);
  font-size: 14px;
}

.menu-toggle {
  display: none;
  min-width: 44px;
  min-height: 44px;
  padding: 10px;
  border: 0;
  border-radius: var(--radius-sm);
  background: var(--color-panel);
  cursor: pointer;
}

.menu-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  margin: 4px auto;
  border-radius: var(--radius-pill);
  background: var(--color-text);
}

.mobile-nav {
  display: none;
}

.mobile-veil {
  display: none;
}

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

.footer-main {
  display: grid;
  grid-template-columns: minmax(240px, 1.2fr) repeat(3, minmax(150px, 1fr));
  gap: clamp(28px, 5vw, 72px);
  padding-top: 64px;
  padding-bottom: 48px;
}

.footer-brand p {
  max-width: 360px;
  margin-top: 18px;
  color: var(--color-muted);
}

.footer-title {
  margin-bottom: 15px;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.04em;
}

.footer-links {
  display: grid;
  gap: 9px;
}

.footer-links a {
  color: var(--color-muted);
  font-size: 14px;
}

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

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

.footer-keywords a {
  display: inline-flex;
  min-height: 31px;
  max-width: 100%;
  align-items: center;
  padding-inline: 10px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-white);
  color: var(--color-muted);
  font-size: 12px;
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding-top: 22px;
  padding-bottom: 26px;
  border-top: 1px solid var(--color-border);
  color: var(--color-muted);
  font-size: 12px;
}

.footer-legal,
.footer-languages {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
}

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

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

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

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

.prose h2,
.prose h3 {
  scroll-margin-top: calc(var(--toc-top) + var(--toc-height) + 24px);
}

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

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

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

.prose blockquote {
  padding: 18px 20px;
  border-left: 4px solid var(--color-accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--color-accent-pale);
}

body:has(.toc-tabs) section[id] {
  scroll-margin-top: calc(var(--toc-top) + var(--toc-height) + 24px);
}

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

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

  .main-nav .nav-link {
    padding-inline: 6px;
    font-size: 12px;
  }

  .language-trigger span {
    display: none;
  }
}

@media (max-width: 980px) {
  :root {
    --header-height: 72px;
    --toc-top: 78px;
  }

  .main-nav,
  .header-tools .language-picker {
    display: none;
  }

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

  .menu-toggle {
    display: block;
  }

  .mobile-veil {
    position: fixed;
    z-index: 90;
    inset: var(--header-height) 0 0;
    background: var(--color-overlay);
  }

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

  .mobile-nav {
    position: fixed;
    z-index: 110;
    top: var(--header-height);
    right: 0;
    left: 0;
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
    overscroll-behavior: contain;
    padding: 10px var(--gutter) 18px;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    background: var(--color-white);
    -webkit-overflow-scrolling: touch;
  }

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

  .mobile-nav a {
    display: flex;
    width: 100%;
    min-height: 48px;
    align-items: center;
    padding: 10px 12px;
    border-bottom: 1px solid var(--color-border);
    font-weight: 700;
  }

  .mobile-nav a.active {
    color: var(--color-accent-dark);
  }

  .mobile-language-title {
    padding: 18px 12px 5px;
    color: var(--color-muted);
    font-size: 11px;
    font-weight: 750;
    letter-spacing: 0.08em;
  }

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

@media (max-width: 768px) {
  h1,
  .hero-title {
    font-size: clamp(28px, 9vw, 40px);
    line-height: 1.12;
  }

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

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

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

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

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

  body {
    overflow-x: clip;
  }

  .header-inner {
    gap: 10px;
  }

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

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

  .login-button {
    min-height: 44px;
    padding-inline: 13px;
  }

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

  .button,
  .primary-cta,
  .secondary-cta {
    max-width: 100%;
  }

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

@media (max-width: 390px) {
  .brand-copy {
    gap: 0;
  }

  .brand-cn {
    display: none;
  }

  .header-tools {
    gap: 4px;
  }

  .login-button {
    padding-inline: 11px;
  }
}

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

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

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