:root {
  --color-bg: #02191d;
  --color-bg-deep: #011216;
  --color-panel: #06242a;
  --color-panel-raised: #0a3036;
  --color-panel-soft: #0c383d;
  --color-border: #1d4a4e;
  --color-border-bright: #36736f;
  --color-accent: #67e8d4;
  --color-accent-soft: #9cf4e7;
  --color-accent-dark: #169e91;
  --color-accent-ink: #032a2a;
  --color-text: #f1f7f4;
  --color-text-muted: #9cb8b5;
  --color-text-dim: #688c89;
  --color-success: #72d7a5;
  --color-warn: #e6b96a;
  --color-error: #f07872;
  --color-grid: #d9fff708;
  --color-grid-strong: #d9fff70d;
  --color-shadow: #00000066;
  --color-shadow-deep: #00000099;
  --color-glow: #67e8d433;
  --color-glow-soft: #67e8d418;
  --color-highlight: #67e8d40f;
  --color-white-soft: #ffffff0d;
  --color-overlay: #011216d9;
  --color-transparent: transparent;

  --font-display: "Iowan Old Style", "Palatino Linotype", "Songti SC", "STSong", Georgia, serif;
  --font-body: "Inter", "Noto Sans SC", "Noto Sans JP", "Noto Sans KR", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;

  --radius-xs: 6px;
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --radius-xl: 30px;
  --radius-pill: 999px;

  --shadow-button: 0 10px 28px var(--color-glow);
  --shadow-panel: 0 28px 80px var(--color-shadow-deep);
  --shadow-card: 0 16px 42px var(--color-shadow);
  --shadow-inset: inset 0 1px 0 var(--color-white-soft);

  --wrap-max: 1240px;
  --header-height: 72px;
  --gutter: clamp(16px, 4vw, 36px);
  --section-space: clamp(72px, 9vw, 128px);
  --toc-top: 84px;
  --transition-fast: 180ms ease;
  --transition-reveal: 620ms cubic-bezier(0.22, 1, 0.36, 1);
}

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

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

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  overflow-x: clip;
  color: var(--color-text);
  background-color: var(--color-bg);
  background-image:
    linear-gradient(var(--color-grid) 1px, var(--color-transparent) 1px),
    linear-gradient(90deg, var(--color-grid) 1px, var(--color-transparent) 1px);
  background-size: 64px 64px;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

main,
section,
article,
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: var(--color-transparent);
}

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

a,
button {
  touch-action: manipulation;
}

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

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

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

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

:not(pre) > code {
  max-width: 100%;
  padding: 0.12em 0.38em;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xs);
  overflow-wrap: anywhere;
  color: var(--color-accent-soft);
  background: var(--color-panel);
  font-size: 0.88em;
}

pre {
  max-width: 100%;
  padding: 20px;
  overflow-x: auto;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  background: var(--color-bg-deep);
  font-family: var(--font-mono);
  font-size: 0.88rem;
  line-height: 1.75;
  overscroll-behavior-inline: contain;
}

pre code {
  white-space: pre;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  padding: 14px 16px;
  border-bottom: 1px solid var(--color-border);
  text-align: left;
  vertical-align: top;
}

th {
  color: var(--color-text);
  background: var(--color-highlight);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
}

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

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

h1,
.display-title {
  font-family: var(--font-display);
  font-size: clamp(52px, 5.3vw, 72px);
  font-weight: 500;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  font-family: var(--font-display);
  font-size: clamp(36px, 4.2vw, 56px);
  font-weight: 500;
  line-height: 1.15;
  letter-spacing: -0.018em;
}

h3 {
  font-size: clamp(20px, 2.2vw, 28px);
  line-height: 1.3;
}

h4 {
  font-size: 1rem;
}

::selection {
  color: var(--color-accent-ink);
  background: var(--color-accent);
}

:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

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

.wrap-narrow {
  width: 100%;
  max-width: calc(800px + (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-tight {
  padding-top: clamp(48px, 6vw, 80px);
  padding-bottom: clamp(48px, 6vw, 80px);
  overflow-x: clip;
}

.section-heading {
  max-width: 760px;
  margin-bottom: clamp(30px, 5vw, 56px);
}

.section-heading p {
  max-width: 640px;
  margin-bottom: 0;
  font-size: clamp(16px, 1.7vw, 19px);
}

.kicker,
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  min-height: 28px;
  max-width: 100%;
  padding: 0 13px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  color: var(--color-text-muted);
  background: var(--color-highlight);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  white-space: nowrap;
  box-shadow: var(--shadow-inset);
}

.kicker-dot,
.status-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border-radius: var(--radius-pill);
  background: var(--color-success);
  box-shadow: 0 0 12px var(--color-success);
}

.title-accent {
  color: var(--color-accent);
  font-style: italic;
  text-shadow: 0 0 34px var(--color-glow);
}

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

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

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

.panel,
.card {
  min-width: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-panel);
  box-shadow: var(--shadow-inset);
}

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

.card {
  padding: 24px;
  transition:
    transform var(--transition-fast),
    border-color var(--transition-fast),
    background-color var(--transition-fast);
}

.card:hover {
  border-color: var(--color-border-bright);
  background: var(--color-panel-raised);
  transform: translateY(-3px);
}

.tilt,
.card-tilt {
  transform: rotate(-0.35deg);
}

.button,
.btn {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  max-width: 100%;
  padding: 0 20px;
  border: 1px solid var(--color-border-bright);
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-weight: 700;
  line-height: 1.2;
  text-align: center;
  transition:
    transform var(--transition-fast),
    border-color var(--transition-fast),
    background-color var(--transition-fast),
    color var(--transition-fast);
}

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

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

.button-primary:hover,
.btn-primary:hover {
  background: var(--color-accent-soft);
}

.button-secondary,
.btn-secondary {
  color: var(--color-text);
  background: var(--color-panel);
  box-shadow: var(--shadow-inset);
}

.button-secondary:hover,
.btn-secondary:hover {
  border-color: var(--color-accent);
  background: var(--color-panel-raised);
}

.button-ghost,
.btn-ghost {
  color: var(--color-text-muted);
  background: var(--color-transparent);
}

.button[disabled],
.btn[disabled] {
  cursor: not-allowed;
  opacity: 0.55;
  transform: none;
}

.button svg,
.btn svg,
.icon {
  width: 17px;
  height: 17px;
  flex: 0 0 auto;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.badge,
.tag {
  display: inline-flex;
  align-items: center;
  min-height: 26px;
  max-width: 100%;
  padding: 3px 10px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  color: var(--color-text-muted);
  background: var(--color-highlight);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  line-height: 1.3;
  text-overflow: ellipsis;
  white-space: nowrap;
}

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

.badge-success {
  border-color: var(--color-success);
  color: var(--color-success);
}

.site-header {
  position: relative;
  z-index: 100;
  height: var(--header-height);
  border-bottom: 1px solid var(--color-grid-strong);
  background: var(--color-bg-deep);
  box-shadow: var(--shadow-inset);
}

.header-inner {
  width: min(1360px, calc(100% - 48px));
  height: 100%;
  margin-inline: auto;
  display: flex;
  align-items: center;
  gap: 22px;
}

.brand {
  min-width: 202px;
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 10px;
}

.brand-mark {
  width: 36px;
  height: 36px;
  flex: 0 0 auto;
  border-radius: var(--radius-sm);
  filter: drop-shadow(0 8px 14px var(--color-glow-soft));
}

.brand-word {
  font-family: var(--font-display);
  font-size: 23px;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.brand-local {
  color: var(--color-text-muted);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.08em;
}

.primary-nav {
  min-width: 0;
  flex: 1 1 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  white-space: nowrap;
}

.primary-nav a {
  position: relative;
  padding: 8px 9px;
  color: var(--color-text-muted);
  font-size: 13px;
  transition: color var(--transition-fast);
}

.primary-nav a:not(:last-child)::after {
  content: "·";
  position: absolute;
  right: -3px;
  color: var(--color-text-dim);
}

.primary-nav a:hover,
.primary-nav a[aria-current="page"] {
  color: var(--color-text);
}

.primary-nav a[aria-current="page"]::before {
  content: "";
  position: absolute;
  right: 10px;
  bottom: 2px;
  left: 10px;
  height: 1px;
  background: var(--color-accent);
  box-shadow: 0 0 10px var(--color-accent);
}

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

.language-picker {
  position: relative;
}

.language-button {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 0 6px;
  border: 0;
  color: var(--color-text-muted);
  background: var(--color-transparent);
  cursor: pointer;
  font-size: 12px;
}

.language-button svg {
  width: 15px;
  height: 15px;
  flex: 0 0 auto;
}

.language-menu {
  position: absolute;
  z-index: 130;
  top: calc(100% + 8px);
  right: 0;
  width: 168px;
  padding: 7px;
  border: 1px solid var(--color-border-bright);
  border-radius: var(--radius-md);
  background: var(--color-panel-raised);
  box-shadow: var(--shadow-card);
}

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

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

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

.login-button {
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border: 1px solid var(--color-border-bright);
  border-radius: var(--radius-sm);
  color: var(--color-text);
  background: var(--color-panel);
  font-size: 13px;
  font-weight: 650;
  box-shadow: var(--shadow-inset);
  transition:
    border-color var(--transition-fast),
    background-color var(--transition-fast);
}

.login-button:hover {
  border-color: var(--color-accent);
  background: var(--color-panel-raised);
}

.menu-toggle {
  min-width: 44px;
  min-height: 44px;
  display: none;
  place-items: center;
  padding: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-panel);
  cursor: pointer;
}

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  width: 18px;
  height: 1px;
  display: block;
  background: var(--color-text);
  transition: transform var(--transition-fast);
}

.menu-toggle-lines {
  position: relative;
}

.menu-toggle-lines::before,
.menu-toggle-lines::after {
  content: "";
  position: absolute;
  left: 0;
}

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

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

.menu-toggle[aria-expanded="true"] .menu-toggle-lines {
  background: var(--color-transparent);
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::before {
  top: 0;
  transform: rotate(45deg);
}

.menu-toggle[aria-expanded="true"] .menu-toggle-lines::after {
  top: 0;
  transform: rotate(-45deg);
}

.mobile-nav {
  position: absolute;
  z-index: 125;
  top: var(--header-height);
  right: 0;
  left: 0;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  padding: 12px var(--gutter) 22px;
  overflow-y: auto;
  border-bottom: 1px solid var(--color-border-bright);
  background: var(--color-bg-deep);
  box-shadow: var(--shadow-panel);
  overscroll-behavior: contain;
}

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

.mobile-nav a {
  min-height: 48px;
  width: 100%;
  display: flex;
  align-items: center;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-muted);
}

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

.mobile-nav-languages {
  padding-top: 12px;
}

.mobile-nav-languages strong {
  display: block;
  padding-block: 8px;
  color: var(--color-text-dim);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
}

.mobile-nav-languages a {
  min-height: 44px;
}

.nav-veil {
  position: fixed;
  z-index: 90;
  inset: var(--header-height) 0 0;
  display: none;
  border: 0;
  background: var(--color-overlay);
}

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

.site-footer {
  position: relative;
  overflow-x: clip;
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-deep);
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(220px, 1.25fr) repeat(3, minmax(150px, 1fr));
  gap: clamp(28px, 5vw, 70px);
  padding-top: 64px;
  padding-bottom: 52px;
}

.footer-brand p {
  max-width: 320px;
  margin-top: 18px;
}

.footer-brand .brand {
  min-width: 0;
}

.footer-column h2 {
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

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

.footer-links a {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding-top: 22px;
  padding-bottom: 28px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-dim);
  font-family: var(--font-mono);
  font-size: 0.72rem;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 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 {
  width: 100%;
  max-width: 48rem;
  margin-inline: auto;
}

.prose h2 {
  margin-top: 2.2em;
  margin-bottom: 0.65em;
  font-size: clamp(30px, 4vw, 44px);
}

.prose h3 {
  margin-top: 1.8em;
  margin-bottom: 0.55em;
}

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

.prose a {
  color: var(--color-accent);
  text-decoration: underline;
  text-decoration-color: var(--color-accent-dark);
  text-underline-offset: 0.18em;
}

.prose blockquote {
  margin-inline: 0;
}

.prose > .data-table {
  display: block;
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

body:has(.toc-tabs) section[id] {
  scroll-margin-top: calc(var(--toc-top) + 72px);
}

@media (max-width: 1180px) {
  .header-inner {
    width: calc(100% - 32px);
    gap: 12px;
  }

  .brand {
    min-width: 164px;
  }

  .brand-local {
    display: none;
  }

  .primary-nav a {
    padding-inline: 6px;
    font-size: 12px;
  }
}

@media (max-width: 980px) {
  .primary-nav,
  .language-picker {
    display: none;
  }

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

  .menu-toggle {
    display: grid;
  }

  .footer-grid {
    grid-template-columns: 1.2fr 1fr 1fr;
  }

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

@media (max-width: 768px) {
  :root {
    --header-height: 64px;
    --toc-top: 72px;
  }

  h1,
  .display-title {
    font-size: clamp(28px, 9.5vw, 40px);
    line-height: 1.12;
    letter-spacing: -0.018em;
  }

  h2 {
    font-size: clamp(30px, 8vw, 42px);
  }

  .site-header {
    height: var(--header-height);
  }

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

  .brand {
    min-width: 0;
  }

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

  .brand-word {
    font-size: 21px;
  }

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

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

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

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

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

  .decorative-label,
  .hero-coordinate,
  .section-watermark {
    display: none;
  }
}

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

  body {
    background-size: 42px 42px;
  }

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

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

  .button-row {
    width: 100%;
  }

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

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

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

  .kicker,
  .eyebrow,
  .badge,
  .tag {
    max-width: 100%;
  }

  th,
  td {
    padding: 12px;
  }
}

@media (max-width: 390px) {
  .brand-word {
    font-size: 19px;
  }

  .login-button {
    padding-inline: 10px;
  }

  .header-inner {
    gap: 7px;
  }
}

@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 {
    opacity: 1;
    transform: none;
  }
}