:root {
  --color-page: #FFFFFF;
  --color-panel: #F6F8FA;
  --color-panel-raised: #EEF2F6;
  --color-ink: #101623;
  --color-muted: #5B6472;
  --color-line: #E4E9EF;
  --color-accent: #10B3C7;
  --color-accent-deep: #0A7E8F;
  --color-sky: #2E9BFF;
  --color-success: #1AA05E;
  --color-warning: #F2AE1C;
  --color-error: #DE3B4E;
  --color-hero: #0D1526;
  --color-hero-panel: #141F37;
  --color-hero-panel-raised: #1A2643;
  --color-hero-line: #25324E;
  --color-hero-text: #F2F5FA;
  --color-hero-muted: #A9B4C8;
  --color-hero-faint: #69758E;
  --color-white: #FFFFFF;
  --color-flag-red: #D0273B;
  --color-flag-blue: #1D4C9C;
  --color-korea-blue: #1255A5;
  --color-korea-red: #D7374A;
  --color-overlay: rgb(13 21 38 / 56%);
  --color-hero-dot: rgb(255 255 255 / 4.5%);
  --color-hero-glass: rgb(255 255 255 / 3%);
  --color-hero-tag: rgb(255 255 255 / 6%);
  --color-hero-tag-hot: rgb(255 255 255 / 20%);
  --color-hero-hot-text: rgb(255 255 255 / 85%);
  --color-shadow-soft: rgb(16 22 35 / 6%);
  --color-shadow-mid: rgb(16 22 35 / 12%);
  --color-shadow-deep: rgb(16 22 35 / 14%);
  --color-accent-glow: rgb(16 179 199 / 32%);
  --color-warning-glow: rgb(242 174 28 / 70%);
  --gradient-accent: linear-gradient(100deg, var(--color-accent) 0%, var(--color-sky) 100%);
  --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', Menlo, monospace;
  --radius-xs: 6px;
  --radius-sm: 9px;
  --radius-md: 14px;
  --radius-lg: 26px;
  --radius-pill: 999px;
  --shadow-card: 0 2px 6px var(--color-shadow-soft), 0 18px 48px var(--color-shadow-deep), 0 44px 88px var(--color-shadow-mid);
  --shadow-drop: 0 8px 28px var(--color-shadow-mid), 0 2px 6px var(--color-shadow-soft);
  --shadow-button: 0 6px 20px var(--color-accent-glow);
  --wrap-max: 1400px;
  --reading-max: 820px;
  --header-height: 64px;
  --gutter: 32px;
  --section-space: 88px;
  --toc-offset: 76px;
  --motion-fast: 160ms;
  --motion-normal: 360ms;
}

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

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

html.nav-open {
  overflow: hidden;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--color-page);
  color: var(--color-ink);
  overflow-x: clip;
  -webkit-font-smoothing: antialiased;
  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,
a {
  -webkit-tap-highlight-color: transparent;
}

button {
  cursor: pointer;
}

a {
  color: var(--color-accent-deep);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.18em;
}

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

p,
ul,
ol,
dl,
blockquote,
pre,
table {
  margin-top: 0;
  margin-bottom: 1.15em;
}

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

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

code {
  overflow-wrap: anywhere;
}

pre {
  max-width: 100%;
  overflow-x: auto;
  padding: 18px;
  border-radius: var(--radius-sm);
  background: var(--color-hero);
  color: var(--color-hero-text);
  -webkit-overflow-scrolling: touch;
}

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

hr {
  height: 1px;
  margin: 32px 0;
  border: 0;
  background: var(--color-line);
}

h1,
h2,
h3,
h4 {
  margin-top: 0;
  color: var(--color-ink);
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.18;
  text-wrap: balance;
}

h1 {
  font-size: clamp(52px, 5vw, 72px);
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(30px, 3vw, 44px);
  letter-spacing: -0.015em;
}

h3 {
  font-size: clamp(21px, 2vw, 28px);
}

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

.wrap {
  width: 100%;
  max-width: var(--wrap-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);
  overflow-x: clip;
}

.section-head {
  max-width: 760px;
  margin-bottom: 34px;
}

.section-kicker {
  margin-bottom: 8px;
  color: var(--color-accent-deep);
  font-family: var(--font-mono);
  font-size: 13px;
}

.section-lead {
  color: var(--color-muted);
  font-size: 17px;
}

.surface {
  border-radius: var(--radius-md);
  background: var(--color-panel);
}

.panel {
  padding: 24px;
  border-radius: var(--radius-md);
  background: var(--color-panel);
  box-shadow: 0 2px 6px var(--color-shadow-soft);
}

.badge,
.tag {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  max-width: 100%;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  overflow: hidden;
  background: var(--color-panel-raised);
  color: var(--color-muted);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.4;
}

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

.btn,
.btn-primary,
.btn-secondary,
.btn-dark,
.btn-small {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: 0;
  border-radius: var(--radius-sm);
  padding: 12px 24px;
  text-align: center;
  text-decoration: none;
  font-weight: 700;
  line-height: 1.3;
  transition: color var(--motion-fast), background var(--motion-fast), border-color var(--motion-fast), box-shadow var(--motion-fast), transform var(--motion-fast);
}

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

.btn-primary:hover {
  color: var(--color-white);
  box-shadow: var(--shadow-button), inset 0 0 0 1px var(--color-warning);
}

.btn-secondary {
  border: 1px solid var(--color-line);
  background: var(--color-page);
  color: var(--color-ink);
}

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

.btn-dark {
  background: var(--color-ink);
  color: var(--color-white);
}

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

.btn-small {
  min-height: 38px;
  padding: 8px 16px;
  font-size: 13px;
}

.btn:focus-visible,
.btn-primary:focus-visible,
.btn-secondary:focus-visible,
.btn-dark:focus-visible,
.btn-small:focus-visible,
a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--color-warning);
  outline-offset: 2px;
}

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

.site-topbar__inner {
  display: flex;
  height: var(--header-height);
  align-items: center;
  gap: 26px;
}

.site-brand {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 9px;
  color: var(--color-ink);
  text-decoration: none;
}

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

.site-brand__logo {
  width: 26px;
  height: 26px;
  flex: 0 0 auto;
}

.site-brand__name {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.site-brand__local {
  color: var(--color-muted);
  font-size: 13px;
  font-weight: 500;
}

.desktop-nav {
  display: flex;
  align-items: center;
  gap: 4px;
}

.desktop-nav > a,
.more-menu > button {
  display: flex;
  min-height: 38px;
  align-items: center;
  gap: 5px;
  border: 0;
  border-radius: var(--radius-sm);
  padding: 7px 12px;
  background: transparent;
  color: var(--color-muted);
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
}

.desktop-nav > a:hover,
.more-menu > button:hover {
  background: var(--color-panel);
  color: var(--color-ink);
}

.desktop-nav > a.is-active,
.more-menu.is-active > button {
  color: var(--color-ink);
  font-weight: 700;
}

.more-menu {
  position: relative;
}

.caret {
  width: 10px;
  height: 10px;
  flex: 0 0 auto;
}

.more-menu__drop,
.language-menu__drop {
  position: absolute;
  top: calc(100% + 6px);
  z-index: 120;
  display: none;
  min-width: 176px;
  padding: 6px;
  border: 1px solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-page);
  box-shadow: var(--shadow-drop);
}

.more-menu__drop {
  left: 0;
}

.more-menu:hover .more-menu__drop,
.more-menu:focus-within .more-menu__drop,
.more-menu.is-open .more-menu__drop,
.language-menu.is-open .language-menu__drop {
  display: block;
}

.more-menu__drop a,
.language-menu__drop a {
  display: block;
  min-height: 40px;
  padding: 9px 12px;
  border-radius: var(--radius-xs);
  color: var(--color-muted);
  text-decoration: none;
  font-size: 14px;
}

.more-menu__drop a:hover,
.language-menu__drop a:hover,
.more-menu__drop a.is-active {
  background: var(--color-panel);
  color: var(--color-ink);
}

.header-tools {
  display: flex;
  margin-left: auto;
  align-items: center;
  gap: 12px;
}

.language-menu {
  position: relative;
}

.language-menu__button {
  display: flex;
  min-height: 38px;
  align-items: center;
  gap: 5px;
  border: 0;
  padding: 6px;
  background: transparent;
  color: var(--color-muted);
  font-size: 13px;
}

.language-menu__drop {
  right: 0;
}

.login-link {
  display: inline-flex;
  min-height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-pill);
  padding: 8px 20px;
  background: var(--color-ink);
  color: var(--color-white);
  text-decoration: none;
  font-size: 14px;
  font-weight: 700;
}

.login-link:hover {
  background: var(--color-accent-deep);
  color: var(--color-white);
}

.menu-toggle {
  display: none;
  width: 44px;
  min-width: 44px;
  height: 44px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border: 0;
  border-radius: var(--radius-sm);
  background: var(--color-panel);
  color: var(--color-ink);
}

.menu-toggle svg {
  width: 22px;
  height: 22px;
}

.mobile-drawer {
  display: none;
}

.mobile-veil {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 89;
  display: none;
  border: 0;
  background: var(--color-overlay);
}

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

.site-footer__grid {
  display: grid;
  grid-template-columns: minmax(220px, 1.3fr) repeat(3, minmax(150px, 1fr));
  gap: 38px;
  padding-top: 54px;
  padding-bottom: 42px;
}

.footer-brand p {
  max-width: 330px;
  margin-top: 16px;
  color: var(--color-muted);
}

.footer-title {
  margin-bottom: 13px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-ink);
}

.footer-links {
  margin: 0;
  padding: 0;
  list-style: none;
}

.footer-links a {
  display: inline-block;
  padding-block: 5px;
  color: var(--color-muted);
  text-decoration: none;
}

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

.site-footer__bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding-top: 18px;
  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);
}

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

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

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

.prose {
  color: var(--color-ink);
  font-size: 16px;
}

.prose h2,
.prose h3 {
  scroll-margin-top: var(--toc-offset);
}

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

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

@media (max-width: 1040px) {
  .desktop-nav > a:nth-of-type(n+4) {
    display: none;
  }

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

@media (max-width: 768px) {
  :root {
    --gutter: 20px;
    --section-space: 66px;
  }

  h1,
  .hero h1 {
    font-size: clamp(28px, 9vw, 40px);
    line-height: 1.12;
    letter-spacing: -0.015em;
  }

  .site-topbar__inner {
    gap: 10px;
  }

  .desktop-nav,
  .header-tools .language-menu {
    display: none;
  }

  .header-tools {
    margin-left: auto;
    gap: 8px;
  }

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

  .login-link {
    min-height: 38px;
    padding-inline: 15px;
  }

  .mobile-drawer {
    position: absolute;
    top: var(--header-height);
    right: 0;
    left: 0;
    z-index: 110;
    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-page);
    box-shadow: var(--shadow-drop);
    -webkit-overflow-scrolling: touch;
  }

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

  .mobile-drawer a {
    display: flex;
    width: 100%;
    min-height: 46px;
    align-items: center;
    border-radius: var(--radius-sm);
    padding: 11px 12px;
    color: var(--color-muted);
    text-decoration: none;
  }

  .mobile-drawer a:hover,
  .mobile-drawer a.is-active {
    background: var(--color-panel);
    color: var(--color-ink);
  }

  .mobile-drawer__label {
    margin: 12px 12px 4px;
    color: var(--color-muted);
    font-family: var(--font-mono);
    font-size: 11px;
  }

  .site-footer__grid {
    gap: 28px;
  }

  .site-footer__bottom {
    align-items: flex-start;
    flex-direction: column;
  }
}

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

  .wrap,
  .reading {
    padding-inline: var(--gutter);
  }

  .site-brand__local {
    display: none;
  }

  .site-brand__name {
    font-size: 17px;
  }

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

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

  .btn,
  .btn-primary,
  .btn-secondary,
  .btn-dark {
    max-width: 100%;
  }
}

@media (max-width: 360px) {
  .login-link {
    padding-inline: 12px;
  }

  .site-brand__logo {
    width: 24px;
    height: 24px;
  }
}

@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;
    transform: none;
  }
}