:root {
  --color-page: #FFFFFF;
  --color-panel: #F6F7F8;
  --color-panel-raised: #FFFFFF;
  --color-panel-deep: #0C1219;
  --color-panel-deeper: #0F1922;
  --color-border: #E4E7EA;
  --color-border-strong: #C8CDD2;
  --color-border-dark: #1D2935;
  --color-border-dark-strong: #374552;
  --color-accent: #00DFA6;
  --color-accent-dark: #0B9E74;
  --color-text: #14181D;
  --color-text-muted: #5B646D;
  --color-text-soft: #89929B;
  --color-text-on-dark: #FFFFFF;
  --color-text-dark-muted: #96A3AE;
  --color-code-dark: #C7D2DC;
  --color-success: #16C860;
  --color-warning: #FF6D4D;
  --color-error: #E5484D;
  --color-cta-ink: #04160E;
  --color-dark-row: #101B26;
  --color-backdrop: rgba(12, 18, 25, 0.46);
  --color-shadow-soft: rgba(12, 18, 25, 0.12);
  --color-shadow-card: rgba(12, 18, 25, 0.26);
  --color-shadow-deep: rgba(0, 0, 0, 0.6);
  --color-shadow-accent: rgba(0, 223, 166, 0.55);
  --color-accent-tint: rgba(0, 223, 166, 0.1);
  --color-success-tint: rgba(22, 200, 96, 0.1);
  --color-warning-tint: rgba(255, 109, 77, 0.1);
  --color-error-tint: rgba(229, 72, 77, 0.1);
  --color-white-tint: rgba(255, 255, 255, 0.08);
  --color-white-border: rgba(255, 255, 255, 0.16);
  --color-flag-white: #F4F6F8;
  --color-flag-red: #CE2B37;
  --color-flag-blue: #26418F;
  --color-flag-kr-red: #CD2E3A;
  --color-flag-kr-blue: #0047A0;
  --color-flag-black: #20242B;
  --color-flag-gold: #F5C400;

  --gradient-accent: linear-gradient(112deg, var(--color-accent) 0%, var(--color-success) 100%);
  --gradient-panel-hover: linear-gradient(112deg, var(--color-accent-tint), var(--color-success-tint));

  --font-display: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Inter', 'Noto Sans SC', -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Consolas, 'Liberation Mono', monospace;

  --radius-xs: 6px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 26px;
  --radius-pill: 999px;

  --shadow-chip: 0 2px 6px -2px var(--color-shadow-soft);
  --shadow-card: 0 36px 72px -36px var(--color-shadow-card), 0 14px 30px -20px var(--color-shadow-card);
  --shadow-console: 0 26px 52px -26px var(--color-shadow-deep);
  --shadow-cta: 0 12px 28px -10px var(--color-shadow-accent);

  --content-max: 1392px;
  --reading-max: 56rem;
  --gutter: clamp(16px, 3vw, 24px);
  --header-height: 63px;
  --toc-offset: 78px;
  --section-space: clamp(58px, 8vw, 104px);
  --transition-fast: 150ms ease;
  --transition-standard: 260ms ease;
}

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

html {
  background: var(--color-page);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.65;
  scroll-behavior: smooth;
  text-size-adjust: 100%;
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  margin: 0;
  overflow-x: clip;
  background: var(--color-page);
}

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

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

svg {
  flex-shrink: 0;
}

img {
  height: auto;
}

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

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

button {
  color: inherit;
}

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

p,
h1,
h2,
h3,
h4,
ul,
ol,
dl,
dd,
blockquote,
pre,
figure {
  margin: 0;
}

ul,
ol {
  padding: 0;
}

ul[role='list'],
ol[role='list'],
.site-nav-list,
.footer-link-list {
  list-style: none;
}

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

h1,
.hero-title {
  max-width: 100%;
  font-size: clamp(52px, 5.2vw, 72px);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(30px, 3.3vw, 46px);
  font-weight: 850;
  line-height: 1.18;
  letter-spacing: -0.018em;
}

h3 {
  font-size: clamp(20px, 2vw, 27px);
  font-weight: 800;
  line-height: 1.28;
}

h4 {
  font-size: 17px;
  font-weight: 800;
  line-height: 1.35;
}

p {
  overflow-wrap: break-word;
}

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

:not(pre) > code {
  max-width: 100%;
  padding: 0.12em 0.38em;
  overflow-wrap: anywhere;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xs);
  background: var(--color-panel);
  font-size: 0.9em;
}

pre {
  max-width: 100%;
  overflow-x: auto;
  overscroll-behavior-inline: contain;
  padding: 20px;
  border: 1px solid var(--color-border-dark);
  border-radius: var(--radius-md);
  background: var(--color-panel-deep);
  color: var(--color-code-dark);
  line-height: 1.75;
  -webkit-overflow-scrolling: touch;
}

pre code {
  padding: 0;
  border: 0;
  background: transparent;
  color: inherit;
  white-space: pre;
}

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

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

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

.wrap {
  max-width: var(--content-max);
}

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

.section {
  padding-top: var(--section-space);
  padding-bottom: var(--section-space);
}

.section-compact {
  padding-top: clamp(36px, 5vw, 64px);
  padding-bottom: clamp(36px, 5vw, 64px);
}

.section-heading {
  max-width: 760px;
  margin-bottom: clamp(26px, 4vw, 44px);
}

.section-heading > p {
  margin-top: 12px;
  color: var(--color-text-muted);
  font-size: clamp(16px, 1.7vw, 19px);
}

.keyword-lock {
  white-space: nowrap;
}

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

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

.panel,
.card {
  min-width: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-panel-raised);
}

.card {
  box-shadow: var(--shadow-chip);
}

.panel-deep {
  border-color: var(--color-border-dark);
  background: var(--color-panel-deep);
  color: var(--color-text-on-dark);
}

.badge,
.tag,
.fact-chip {
  display: inline-flex;
  max-width: 100%;
  min-height: 28px;
  align-items: center;
  gap: 7px;
  padding: 4px 11px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-page);
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  font-size: 11.5px;
  line-height: 1.35;
}

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

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

.tag {
  color: var(--color-text);
  box-shadow: var(--shadow-chip);
}

.btn {
  display: inline-flex;
  min-height: 46px;
  max-width: 100%;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 22px;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 800;
  line-height: 1.2;
  text-align: center;
  transition: transform var(--transition-fast), border-color var(--transition-fast), background var(--transition-fast), color var(--transition-fast);
}

.btn svg {
  width: 16px;
  height: 16px;
}

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

.btn-primary {
  background: var(--gradient-accent);
  color: var(--color-cta-ink);
  box-shadow: var(--shadow-cta);
}

.btn-secondary {
  border-color: var(--color-border-strong);
  background: var(--color-page);
  color: var(--color-text);
}

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

.btn-dark {
  background: var(--color-text);
  color: var(--color-text-on-dark);
}

.btn-outline-light {
  border-color: var(--color-border-dark-strong);
  background: transparent;
  color: var(--color-text-on-dark);
}

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

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

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

.reveal {
  transition: opacity 520ms ease, transform 520ms ease;
}

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

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

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

.site-header-inner {
  width: 100%;
  max-width: var(--content-max);
  min-height: var(--header-height);
  margin-inline: auto;
  padding-inline: var(--gutter);
  display: flex;
  align-items: center;
  gap: 24px;
}

.site-brand {
  display: inline-flex;
  flex: none;
  align-items: center;
  gap: 9px;
}

.site-brand-logo {
  width: 31px;
  height: 31px;
  object-fit: contain;
}

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

.site-brand-name {
  font-family: var(--font-display);
  font-size: 17.5px;
  font-weight: 850;
  letter-spacing: -0.01em;
}

.site-brand-local {
  color: var(--color-text-muted);
  font-size: 12px;
  font-weight: 600;
}

.desktop-nav {
  flex: 1;
}

.site-nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.site-nav-link {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  gap: 6px;
  padding: 7px 9px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  font-weight: 650;
  white-space: nowrap;
  transition: color var(--transition-fast), background var(--transition-fast);
}

.site-nav-link svg {
  width: 15px;
  height: 15px;
  color: var(--color-text-muted);
}

.site-nav-link:hover,
.site-nav-link.is-active {
  background: var(--color-panel);
  color: var(--color-accent-dark);
}

.site-nav-link:hover svg,
.site-nav-link.is-active svg {
  color: var(--color-accent-dark);
}

.header-tools {
  display: flex;
  flex: none;
  align-items: center;
  gap: 9px;
}

.language-menu {
  position: relative;
}

.language-toggle {
  min-height: 36px;
  padding: 6px 13px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-page);
  color: var(--color-text-muted);
  cursor: pointer;
  font-size: 12px;
  white-space: nowrap;
}

.language-toggle:hover {
  border-color: var(--color-border-strong);
  color: var(--color-text);
}

.language-popover {
  position: absolute;
  top: calc(100% + 9px);
  right: 0;
  z-index: 12;
  width: 168px;
  padding: 6px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-page);
  box-shadow: var(--shadow-card);
}

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

.language-popover a {
  display: flex;
  min-height: 40px;
  align-items: center;
  padding: 8px 11px;
  border-radius: var(--radius-sm);
  font-size: 13px;
}

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

.header-login {
  min-height: 38px;
  padding: 8px 18px;
  border-radius: var(--radius-pill);
  background: var(--color-text);
  color: var(--color-text-on-dark);
  font-size: 13px;
  font-weight: 800;
  white-space: nowrap;
}

.header-login:hover {
  background: var(--color-panel-deep);
}

.menu-toggle {
  display: none;
  width: 44px;
  min-width: 44px;
  height: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-page);
  cursor: pointer;
}

.menu-toggle svg {
  width: 21px;
  height: 21px;
}

.mobile-nav {
  display: none;
}

.mobile-nav[hidden] {
  display: none;
}

.mobile-nav-inner {
  padding: 8px var(--gutter) 16px;
}

.mobile-nav a {
  display: flex;
  width: 100%;
  min-height: 46px;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  font-weight: 700;
}

.mobile-nav a svg {
  width: 18px;
  height: 18px;
  color: var(--color-text-muted);
}

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

.mobile-language-list {
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid var(--color-border);
}

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

.site-footer-main {
  display: grid;
  grid-template-columns: minmax(220px, 1.2fr) repeat(3, minmax(150px, 1fr));
  gap: 38px;
  padding-top: 48px;
  padding-bottom: 42px;
}

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

.footer-brand-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer-logo {
  width: 34px;
  height: 34px;
  object-fit: contain;
}

.footer-brand-row strong {
  font-family: var(--font-display);
  font-size: 19px;
}

.footer-brand p {
  margin-top: 15px;
  color: var(--color-text-muted);
}

.footer-column h2 {
  margin-bottom: 14px;
  font-size: 14px;
  letter-spacing: 0;
}

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

.footer-link-list a {
  color: var(--color-text-muted);
  font-size: 13px;
}

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

.footer-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.footer-keywords a {
  display: inline-flex;
  max-width: 100%;
  padding: 5px 9px;
  overflow: hidden;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-page);
  color: var(--color-text-muted);
  font-size: 11.5px;
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding-top: 18px;
  padding-bottom: 20px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 12px;
}

.footer-legal,
.footer-languages {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

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

.prose {
  color: var(--color-text);
  font-size: 16px;
  line-height: 1.82;
}

.prose > * + * {
  margin-top: 1.15em;
}

.prose h2 {
  margin-top: 2.2em;
}

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

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

.prose li + li {
  margin-top: 0.45em;
}

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

.prose table {
  border-collapse: collapse;
}

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

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

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

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

  .mobile-nav.is-open {
    position: absolute;
    top: 100%;
    right: 0;
    left: 0;
    z-index: 102;
    display: block;
    max-height: calc(100dvh - var(--header-height));
    overflow-y: auto;
    overscroll-behavior: contain;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    background: var(--color-page);
    box-shadow: var(--shadow-card);
  }
}

@media (max-width: 768px) {
  .keyword-lock {
    white-space: normal;
  }

  h1,
  .hero-title {
    font-size: clamp(32px, 9.5vw, 40px);
    line-height: 1.12;
  }

  h2 {
    font-size: clamp(27px, 7.5vw, 36px);
  }

  .section {
    padding-top: 58px;
    padding-bottom: 58px;
  }

  .site-brand-local,
  .language-menu {
    display: none;
  }

  .site-header-inner {
    gap: 10px;
  }

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

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

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

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

  .tilt,
  [class*='tilt-'] {
    transform: none !important;
  }
}

@media (max-width: 480px) {
  .site-brand-copy {
    gap: 0;
  }

  .site-brand-local {
    display: none;
  }

  .site-brand-logo {
    width: 29px;
    height: 29px;
  }

  .site-brand-name {
    font-size: 16px;
  }

  .header-login {
    min-height: 38px;
    padding-inline: 13px;
  }

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

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

  .btn-row,
  .btn-row .btn {
    width: 100%;
  }
}

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

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

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