:root {
  --color-canvas: #FFFFFF;
  --color-panel: #F6FAFD;
  --color-panel-strong: #EDF3F9;
  --color-line: #E3EAF1;
  --color-accent: #0A9BE0;
  --color-accent-dark: #0678B4;
  --color-ink: #101F2C;
  --color-muted: #5B6B79;
  --color-success: #1FA971;
  --color-warning: #E8960F;
  --color-error: #D9463F;
  --color-flag-red: #CE3B33;
  --color-flag-blue: #2A4C9B;
  --color-flag-gold: #F2C438;
  --color-flag-ink: #20242B;
  --color-white: #FFFFFF;
  --color-halo: rgba(10, 155, 224, 0.10);
  --color-button-shadow: rgba(10, 155, 224, 0.30);
  --color-panel-shadow: rgba(16, 31, 44, 0.10);
  --color-soft-shadow: rgba(16, 31, 44, 0.05);
  --color-hover-shadow: rgba(16, 31, 44, 0.08);
  --shadow-button: 0 10px 22px var(--color-button-shadow);
  --shadow-panel: 0 26px 52px var(--color-panel-shadow), 0 7px 18px var(--color-soft-shadow);
  --shadow-card-hover: 0 14px 30px var(--color-hover-shadow);
  --font-display: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', ui-monospace, 'SFMono-Regular', Consolas, 'Courier New', monospace;
  --radius-sm: 10px;
  --radius-md: 18px;
  --radius-lg: 26px;
  --radius-xl: 34px;
  --radius-pill: 999px;
  --content-max: 1320px;
  --reading-max: 48rem;
  --header-height: 64px;
  --gutter: clamp(16px, 3vw, 30px);
  --section-space: clamp(64px, 9vw, 116px);
  --toc-offset: 76px;
  --motion-fast: 180ms;
  --motion-base: 260ms;
  --ease-standard: cubic-bezier(0.2, 0.7, 0.2, 1);
}

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

html {
  margin: 0;
  padding: 0;
  scroll-behavior: smooth;
  overflow-x: clip;
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 0;
  margin: 0;
  padding: 0;
  overflow-x: clip;
  background: var(--color-canvas);
  color: var(--color-ink);
  font-family: var(--font-body);
  line-height: 1.7;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

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

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

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

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

button {
  border: 0;
}

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

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

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

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

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

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

code {
  overflow-wrap: anywhere;
}

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

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

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

h1,
.hero-title {
  margin-bottom: 20px;
  font-size: clamp(52px, 5.2vw, 72px);
  font-weight: 800;
  letter-spacing: -0.015em;
  line-height: 1.1;
}

h2 {
  margin-bottom: 18px;
  font-size: clamp(32px, 3.3vw, 48px);
  font-weight: 800;
  line-height: 1.16;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2vw, 28px);
  line-height: 1.3;
}

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

.wrap {
  width: 100%;
  max-width: var(--content-max);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.reading {
  width: 100%;
  max-width: var(--reading-max);
  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, 72px);
  padding-bottom: clamp(44px, 6vw, 72px);
}

.section-heading {
  max-width: 760px;
  margin-bottom: 38px;
}

.section-kicker,
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  max-width: 100%;
  margin-bottom: 14px;
  color: var(--color-accent-dark);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  overflow-wrap: anywhere;
  text-transform: uppercase;
}

.dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  flex: 0 0 auto;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
}

.dot-success {
  background: var(--color-success);
}

.dot-warning {
  background: var(--color-warning);
}

.dot-error {
  background: var(--color-error);
}

.gradient-text {
  background: linear-gradient(94deg, var(--color-accent) 0%, var(--color-accent-dark) 44%, var(--color-warning) 100%);
  color: transparent;
  background-clip: text;
  -webkit-background-clip: text;
}

.btn {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 11px 28px;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  cursor: pointer;
  font-weight: 700;
  line-height: 1.2;
  text-align: center;
  text-decoration: none;
  transition: color var(--motion-fast) var(--ease-standard), background var(--motion-fast) var(--ease-standard), border-color var(--motion-fast) var(--ease-standard), transform var(--motion-fast) var(--ease-standard), box-shadow var(--motion-fast) var(--ease-standard);
}

.btn:hover {
  transform: translateY(-2px);
  text-decoration: none;
}

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

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

.btn-secondary {
  border-color: var(--color-line);
  background: var(--color-canvas);
  color: var(--color-ink);
}

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

.btn-muted {
  background: var(--color-panel-strong);
  color: var(--color-ink);
}

.btn-danger {
  background: var(--color-error);
  color: var(--color-white);
}

.btn-small {
  min-height: 40px;
  padding: 8px 20px;
  font-size: 14px;
}

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

.icon-inline {
  width: 20px;
  height: 20px;
  flex: 0 0 auto;
}

.badge,
.fact-pill,
.tag {
  display: inline-flex;
  max-width: 100%;
  align-items: center;
  gap: 8px;
  padding: 7px 12px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 600;
  overflow: hidden;
  overflow-wrap: anywhere;
}

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

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

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

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

.card {
  padding: clamp(22px, 3vw, 34px);
  transition: transform var(--motion-base) var(--ease-standard), box-shadow var(--motion-base) var(--ease-standard);
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-card-hover);
}

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

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

.grid-2,
.grid-3,
.grid-4 {
  display: grid;
  gap: 18px;
}

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

.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid-4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

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

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

.site-brand {
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 10px;
  color: var(--color-ink);
  text-decoration: none;
}

.site-brand:hover {
  color: var(--color-ink);
}

.brand-logo {
  width: 30px;
  height: 30px;
  flex: 0 0 auto;
}

.brand-word {
  font-size: 19px;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.brand-local {
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 500;
}

.desktop-nav {
  display: flex;
  min-width: 0;
  flex: 1 1 auto;
  align-items: stretch;
  gap: 1px;
}

.desktop-nav a {
  position: relative;
  display: inline-flex;
  min-height: var(--header-height);
  align-items: center;
  padding-inline: 12px;
  color: var(--color-muted);
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  white-space: nowrap;
}

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

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

.desktop-nav a.is-active::after {
  position: absolute;
  right: 11px;
  bottom: 0;
  left: 11px;
  height: 3px;
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
  background: var(--color-accent);
  content: "";
}

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

.language-wrap {
  position: relative;
}

.language-button {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  gap: 6px;
  padding: 7px 8px;
  background: transparent;
  color: var(--color-muted);
  cursor: pointer;
  font-size: 13px;
}

.language-button:hover {
  color: var(--color-ink);
}

.language-menu {
  position: absolute;
  top: calc(100% + 9px);
  right: 0;
  z-index: 125;
  display: none;
  width: 180px;
  padding: 8px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-canvas);
  box-shadow: var(--shadow-card-hover);
}

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

.language-menu a {
  display: flex;
  min-height: 42px;
  align-items: center;
  padding: 8px 11px;
  border-radius: var(--radius-sm);
  color: var(--color-muted);
  text-decoration: none;
}

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

.header-login {
  min-height: 36px;
  padding: 8px 21px;
}

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

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  display: block;
  width: 19px;
  height: 2px;
  border-radius: var(--radius-pill);
  background: var(--color-ink);
}

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

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

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

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

.mobile-nav {
  position: absolute;
  top: 100%;
  right: 0;
  left: 0;
  z-index: 120;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 10px var(--gutter) 20px;
  border-top: 1px solid var(--color-line);
  background: var(--color-canvas);
  -webkit-overflow-scrolling: touch;
}

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

.mobile-nav a {
  display: flex;
  width: 100%;
  min-height: 48px;
  align-items: center;
  padding: 11px 12px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-ink);
  font-weight: 600;
  text-decoration: none;
}

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

.mobile-language-list {
  padding-top: 10px;
}

.mobile-language-list a {
  color: var(--color-muted);
  font-weight: 500;
}

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

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

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

.footer-main {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1fr 0.8fr;
  gap: 42px;
  padding-top: 58px;
  padding-bottom: 46px;
}

.footer-brand p {
  max-width: 360px;
  margin-top: 18px;
  font-size: 14px;
}

.footer-title {
  margin-bottom: 14px;
  color: var(--color-ink);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.08em;
}

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

.footer-links a {
  width: fit-content;
  color: var(--color-muted);
  font-size: 14px;
  text-decoration: none;
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding-top: 20px;
  padding-bottom: 24px;
  border-top: 1px solid var(--color-line);
  color: var(--color-muted);
  font-size: 13px;
}

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

.footer-legal a {
  color: var(--color-muted);
  text-decoration: none;
}

.prose {
  font-size: 17px;
}

.prose p,
.prose li {
  line-height: 1.85;
}

.prose h2 {
  margin-top: 2.3em;
}

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

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

.prose > *:first-child {
  margin-top: 0;
}

.reveal {
  transition: opacity 620ms var(--ease-standard), transform 620ms var(--ease-standard);
}

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

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

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

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

.hide-visually {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  margin: -1px;
  padding: 0;
  clip-path: inset(50%);
  white-space: nowrap;
}

@media (max-width: 1120px) {
  .desktop-nav a {
    padding-inline: 8px;
    font-size: 13px;
  }

  .header-row {
    gap: 14px;
  }

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

  .footer-language {
    grid-column: 2 / 4;
  }
}

@media (max-width: 900px) {
  .desktop-nav,
  .language-wrap {
    display: none;
  }

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

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

  .grid-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .grid-3 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

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

@media (max-width: 768px) {
  h1,
  .hero-title {
    font-size: clamp(28px, 9.5vw, 40px);
    line-height: 1.12;
    letter-spacing: -0.01em;
  }

  h2 {
    font-size: clamp(27px, 7vw, 36px);
  }

  .prose {
    font-size: 16px;
  }

  .header-login {
    min-height: 36px;
    padding-inline: 16px;
  }

  .brand-local {
    display: none;
  }

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

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

  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: minmax(0, 1fr);
  }

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

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

  .footer-main {
    grid-template-columns: minmax(0, 1fr);
    gap: 30px;
  }

  .btn {
    padding-inline: 22px;
  }

  .header-row {
    gap: 8px;
  }

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

  .brand-logo {
    width: 28px;
    height: 28px;
  }

  .section,
  .section-compact {
    overflow-x: clip;
  }
}

@media (max-width: 370px) {
  .header-login {
    padding-inline: 12px;
    font-size: 13px;
  }

  .site-brand {
    gap: 7px;
  }

  .menu-toggle {
    width: 42px;
    min-width: 42px;
  }
}

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

  *,
  *::before,
  *::after {
    animation: none !important;
    scroll-behavior: auto !important;
    transition: none !important;
  }

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