:root {
  --color-bg: #F4F4F5;
  --color-panel: #FFFFFF;
  --color-panel-alt: #ECECEF;
  --color-border: #DEDEE4;
  --color-accent: #6159D6;
  --color-accent-dark: #4740AC;
  --color-text: #2C2B34;
  --color-muted: #6C6B76;
  --color-success: #2FA98C;
  --color-warning: #E8A23C;
  --color-error: #E4605E;
  --color-tint-lavender: #B4ABEA;
  --color-tint-teal: #84CDB7;
  --color-tint-orange: #F1C289;
  --color-tint-cream: #F2DE9E;
  --color-hill-far: #E6F2ED;
  --color-hill-mid: #CFE8DD;
  --color-hill-near: #B2DCCB;
  --color-bush: #5FB79B;
  --color-bush-dark: #3D9C80;
  --color-flag-red: #DE544D;
  --color-flag-blue: #3D5FA8;
  --color-flag-green: #3F9B6E;
  --color-flag-white: #FFFFFF;
  --color-focus: #4740AC;
  --color-overlay: rgba(44, 43, 52, 0.38);
  --color-shadow-soft: rgba(44, 43, 52, 0.14);
  --color-shadow-accent: rgba(97, 89, 214, 0.48);
  --color-shadow-dark: rgba(71, 64, 172, 0.28);
  --font-display: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', -apple-system, 'PingFang SC', 'Hiragino Sans', 'Malgun Gothic', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', -apple-system, 'PingFang SC', 'Hiragino Sans', 'Malgun Gothic', sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;
  --radius-xl: 28px;
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --radius-pill: 999px;
  --shadow-soft: 0 1px 2px rgba(44, 43, 52, 0.05), 0 10px 30px -12px var(--color-shadow-soft);
  --shadow-button: 0 1px 2px var(--color-shadow-dark), 0 12px 26px -10px var(--color-shadow-accent);
  --shadow-float: 0 2px 6px var(--color-shadow-dark), 0 16px 34px -12px var(--color-shadow-accent);
  --shadow-device: 0 22px 55px -26px var(--color-shadow-soft), 0 5px 14px -8px var(--color-shadow-dark);
  --content-max: 1180px;
  --content-wide: 1360px;
  --gutter: clamp(16px, 4vw, 32px);
  --header-height: 72px;
  --section-space: clamp(72px, 9vw, 128px);
  --toc-offset: 88px;
  --transition-fast: 160ms ease;
  --transition-medium: 480ms cubic-bezier(0.22, 1, 0.36, 1);
}

*,
*::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;
  margin: 0;
  overflow-x: clip;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.68;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

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

svg {
  flex-shrink: 0;
}

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

button {
  border: 0;
}

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

ul,
ol {
  margin: 0;
  padding: 0;
}

ul {
  list-style: none;
}

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

table {
  border-collapse: collapse;
}

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

:not(pre) > code {
  overflow-wrap: anywhere;
  border-radius: var(--radius-sm);
  background: var(--color-panel-alt);
  padding: 0.16em 0.42em;
  color: var(--color-accent-dark);
  font-size: 0.9em;
}

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

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

::selection {
  background: var(--color-tint-lavender);
  color: var(--color-text);
}

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

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

.wrap,
.wrap-wide,
.prose-wrap {
  width: 100%;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.wrap {
  max-width: calc(var(--content-max) + var(--gutter) * 2);
}

.wrap-wide {
  max-width: calc(var(--content-wide) + var(--gutter) * 2);
}

.prose-wrap {
  max-width: calc(850px + var(--gutter) * 2);
}

.section {
  position: relative;
  overflow-x: clip;
  padding-top: var(--section-space);
  padding-bottom: var(--section-space);
}

.section--compact {
  padding-top: clamp(48px, 6vw, 80px);
  padding-bottom: clamp(48px, 6vw, 80px);
}

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

.section-head {
  max-width: 780px;
  margin-bottom: clamp(32px, 5vw, 56px);
}

.section-head--center {
  margin-inline: auto;
  text-align: center;
}

.eyebrow {
  display: inline-flex;
  min-height: 32px;
  align-items: center;
  gap: 8px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  padding: 5px 15px;
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 650;
  box-shadow: var(--shadow-soft);
}

.eyebrow-dot {
  width: 8px;
  height: 8px;
  flex-shrink: 0;
  border-radius: var(--radius-pill);
  background: var(--color-success);
}

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

h1,
.display-title {
  font-size: clamp(52px, 5vw, 72px);
  font-weight: 800;
  line-height: 1.12;
  letter-spacing: -0.015em;
}

h2 {
  font-size: clamp(34px, 4vw, 52px);
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: -0.012em;
}

h3 {
  font-size: clamp(22px, 2.4vw, 30px);
  font-weight: 760;
  line-height: 1.28;
}

h4 {
  font-size: 18px;
  font-weight: 730;
}

.title-accent,
.text-accent {
  color: var(--color-accent);
}

.lead {
  max-width: 720px;
  color: var(--color-muted);
  font-size: clamp(18px, 2vw, 21px);
  line-height: 1.72;
}

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

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

.btn-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
}

.btn {
  display: inline-flex;
  min-width: 24px;
  min-height: 50px;
  align-items: center;
  justify-content: center;
  gap: 9px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  padding: 12px 28px;
  cursor: pointer;
  font-weight: 750;
  line-height: 1.2;
  transition: transform var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast), box-shadow var(--transition-fast);
}

.btn:hover {
  transform: translateY(-2px);
}

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

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

.btn--secondary {
  border-color: var(--color-border);
  background: var(--color-panel);
  color: var(--color-text);
  box-shadow: var(--shadow-soft);
}

.btn--secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

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

.btn--small {
  min-height: 42px;
  padding: 9px 20px;
  font-size: 14px;
}

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

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

.card {
  overflow: clip;
}

.badge,
.tag {
  display: inline-flex;
  min-height: 28px;
  max-width: 100%;
  align-items: center;
  gap: 7px;
  overflow: hidden;
  border-radius: var(--radius-pill);
  padding: 4px 11px;
  font-size: 12px;
  font-weight: 700;
  line-height: 1.25;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.badge {
  background: var(--color-panel-alt);
  color: var(--color-muted);
}

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

.badge--success {
  background: var(--color-hill-mid);
  color: var(--color-bush-dark);
}

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

.site-top {
  position: relative;
  z-index: 80;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-panel);
}

.site-nav-shell {
  width: 100%;
  max-width: var(--content-wide);
  height: var(--header-height);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 22px;
}

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

.site-brand img {
  width: 30px;
  height: 30px;
}

.brand-english {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 820;
  letter-spacing: -0.02em;
}

.brand-local {
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 580;
}

.desktop-nav {
  display: flex;
  align-items: center;
  gap: 2px;
  margin-left: auto;
}

.desktop-nav a {
  display: inline-flex;
  min-height: 42px;
  align-items: center;
  gap: 7px;
  border-radius: var(--radius-pill);
  padding: 8px 11px;
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 650;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.desktop-nav a:hover {
  background: var(--color-panel-alt);
  color: var(--color-text);
}

.desktop-nav a:hover svg,
.desktop-nav a.is-active,
.desktop-nav a.is-active svg {
  color: var(--color-accent);
}

.header-tools {
  display: flex;
  align-items: center;
  gap: 9px;
  flex-shrink: 0;
}

.language-picker {
  position: relative;
}

.language-toggle {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border-radius: var(--radius-pill);
  background: transparent;
  color: var(--color-muted);
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
}

.language-toggle:hover {
  background: var(--color-panel-alt);
  color: var(--color-text);
}

.language-menu {
  position: absolute;
  top: calc(100% + 9px);
  right: 0;
  width: 168px;
  display: none;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-panel);
  padding: 6px;
  box-shadow: var(--shadow-soft);
}

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

.language-menu a {
  display: flex;
  min-height: 42px;
  align-items: center;
  border-radius: var(--radius-sm);
  padding: 8px 11px;
  color: var(--color-muted);
  font-size: 14px;
}

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

.header-login {
  display: inline-flex;
  min-height: 42px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
  padding: 9px 21px;
  color: var(--color-panel);
  font-size: 14px;
  font-weight: 750;
  box-shadow: var(--shadow-button);
}

.header-login:hover {
  background: var(--color-accent-dark);
}

.menu-toggle {
  display: none;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-pill);
  background: var(--color-panel-alt);
  cursor: pointer;
}

.menu-toggle-lines {
  position: relative;
  width: 19px;
  height: 14px;
}

.menu-toggle-lines::before,
.menu-toggle-lines::after,
.menu-toggle-lines span {
  position: absolute;
  left: 0;
  width: 19px;
  height: 2px;
  border-radius: var(--radius-pill);
  background: var(--color-text);
  content: "";
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.menu-toggle-lines::before {
  top: 0;
}

.menu-toggle-lines span {
  top: 6px;
}

.menu-toggle-lines::after {
  top: 12px;
}

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

.menu-toggle[aria-expanded="true"] .menu-toggle-lines span {
  opacity: 0;
}

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

.mobile-nav {
  display: none;
}

.mobile-veil {
  display: none;
}

.site-footer {
  position: relative;
  overflow-x: clip;
  border-top: 1px solid var(--color-border);
  background: var(--color-panel);
  padding-top: 64px;
  padding-bottom: 28px;
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(220px, 1.25fr) repeat(3, minmax(150px, 1fr));
  gap: 42px;
}

.footer-brand {
  max-width: 330px;
}

.footer-brandline {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
}

.footer-brandline img {
  width: 32px;
  height: 32px;
}

.footer-brand p,
.footer-column a {
  color: var(--color-muted);
  font-size: 14px;
}

.footer-column h2 {
  margin-bottom: 14px;
  font-size: 15px;
  font-weight: 760;
}

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

.footer-column a {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
}

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

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 16px;
  margin-top: 48px;
  border-top: 1px solid var(--color-border);
  padding-top: 22px;
  color: var(--color-muted);
  font-size: 13px;
}

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

.reveal {
  transition: opacity 620ms ease, transform 620ms cubic-bezier(0.22, 1, 0.36, 1);
}

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

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

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

.prose > * + * {
  margin-top: 1.25em;
}

.prose h2 {
  margin-top: 2.1em;
}

.prose h3 {
  margin-top: 1.7em;
}

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

.prose ul,
.prose ol {
  padding-left: 1.4em;
}

.prose ul {
  list-style: disc;
}

.prose ol {
  list-style: decimal;
}

.prose a:not(.btn) {
  color: var(--color-accent-dark);
  text-decoration: underline;
  text-decoration-color: var(--color-tint-lavender);
  text-underline-offset: 0.18em;
}

body:has(.toc-tabs) section[id] {
  scroll-margin-top: calc(var(--toc-offset) + 20px);
}

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

  .desktop-nav a {
    padding-inline: 10px;
  }

  .brand-local {
    display: none;
  }
}

@media (max-width: 860px) {
  .desktop-nav,
  .header-tools .language-picker {
    display: none;
  }

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

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

  .mobile-veil {
    position: fixed;
    inset: var(--header-height) 0 0;
    z-index: 77;
    background: var(--color-overlay);
  }

  .site-top.menu-open .mobile-veil {
    display: block;
  }

  .mobile-nav {
    position: fixed;
    top: var(--header-height);
    right: 0;
    z-index: 79;
    width: min(390px, 100%);
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
    overscroll-behavior: contain;
    border-top: 1px solid var(--color-border);
    background: var(--color-panel);
    padding: 12px var(--gutter) 20px;
    box-shadow: var(--shadow-soft);
  }

  .site-top.menu-open .mobile-nav {
    display: block;
  }

  .mobile-nav ul {
    display: grid;
  }

  .mobile-nav a {
    display: flex;
    width: 100%;
    min-height: 48px;
    align-items: center;
    gap: 11px;
    border-bottom: 1px solid var(--color-border);
    padding: 11px 8px;
    color: var(--color-muted);
    font-weight: 650;
  }

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

  .mobile-language-title {
    margin: 18px 8px 5px;
    color: var(--color-muted);
    font-size: 12px;
    font-weight: 750;
    letter-spacing: 0.05em;
  }

  .mobile-language-list a {
    border-bottom: 0;
  }
}

@media (max-width: 768px) {
  h1,
  .display-title {
    font-size: clamp(30px, 9.5vw, 40px);
    line-height: 1.14;
    letter-spacing: -0.012em;
  }

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

  .section {
    padding-top: 72px;
    padding-bottom: 72px;
  }

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

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

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

@media (max-width: 640px) {
  :root {
    --gutter: 16px;
    --header-height: 64px;
    --toc-offset: 78px;
  }

  .site-nav-shell {
    gap: 8px;
  }

  .site-brand {
    gap: 7px;
  }

  .site-brand img {
    width: 27px;
    height: 27px;
  }

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

  .header-login {
    min-height: 40px;
    padding-inline: 15px;
  }

  .btn-row {
    width: 100%;
  }

  .btn-row .btn {
    flex: 1 1 140px;
  }

  .panel {
    padding: 20px;
  }

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

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

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

@media (max-width: 380px) {
  .header-login {
    padding-inline: 12px;
    font-size: 13px;
  }

  .brand-english {
    font-size: 17px;
  }
}

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

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

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