:root {
  --color-bg: #070B12;
  --color-bg-deep: #05080D;
  --color-panel: #0B111B;
  --color-panel-raised: #111925;
  --color-panel-soft: #151E2B;
  --color-border: #3A4452;
  --color-border-soft: #242E3B;
  --color-accent: #98FFB8;
  --color-accent-dark: #23633B;
  --color-text: #F1F4F2;
  --color-text-muted: #A5ADB8;
  --color-text-dim: #737D8A;
  --color-success: #98FFB8;
  --color-warn: #CED3DB;
  --color-error: #88919E;
  --color-transparent: transparent;
  --color-grid: rgba(165, 173, 184, 0.055);
  --color-accent-haze: rgba(152, 255, 184, 0.09);
  --color-accent-line: rgba(152, 255, 184, 0.34);
  --color-accent-glow: rgba(152, 255, 184, 0.24);
  --color-white-soft: rgba(241, 244, 242, 0.08);
  --color-overlay: rgba(5, 8, 13, 0.78);
  --color-flag-red: #D7565B;
  --color-flag-deep-red: #B93542;
  --color-flag-blue: #3F68A8;
  --color-flag-deep-blue: #253F7A;
  --color-flag-white: #F1F4F2;
  --color-flag-black: #171B22;

  --font-display: 'Inter', 'Noto Sans SC', 'Noto Sans JP', 'Noto Sans KR', system-ui, sans-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-none: 0;
  --radius-xs: 3px;
  --radius-sm: 6px;
  --radius-pill: 999px;

  --header-height: 68px;
  --page-width: 1320px;
  --content-width: 1040px;
  --reading-width: 768px;
  --gutter: clamp(16px, 4vw, 32px);
  --section-space: clamp(64px, 9vw, 120px);
  --toc-top: 68px;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-md: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.375rem;

  --transition-fast: 160ms ease;
  --transition-medium: 320ms ease;
}

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

html {
  min-width: 0;
  color-scheme: dark;
  background: var(--color-bg);
  scroll-behavior: smooth;
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 0;
  margin: 0;
  overflow-x: clip;
  color: var(--color-text);
  background: var(--color-bg);
  font-family: var(--font-body);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

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

img {
  height: auto;
}

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

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

button {
  border: 0;
}

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

a:not([class]) {
  color: var(--color-accent);
  text-decoration: underline;
  text-decoration-color: var(--color-accent-line);
  text-underline-offset: 0.18em;
}

a:not([class]):hover {
  text-decoration-color: var(--color-accent);
}

p,
ul,
ol,
dl,
blockquote,
pre,
table {
  margin-top: 0;
  margin-bottom: 1.25rem;
}

ul,
ol {
  padding-left: 1.35rem;
}

li + li {
  margin-top: 0.45rem;
}

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

h1 {
  font-size: clamp(52px, 6vw, 72px);
  font-weight: 790;
  line-height: 1.1;
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(2rem, 4vw, 3.25rem);
  font-weight: 730;
  line-height: 1.16;
  letter-spacing: -0.018em;
}

h3 {
  font-size: clamp(1.25rem, 2.5vw, 1.75rem);
  font-weight: 680;
  line-height: 1.3;
}

h4 {
  font-size: 1rem;
  font-weight: 680;
  line-height: 1.4;
}

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

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

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

code {
  overflow-wrap: anywhere;
  color: var(--color-accent);
}

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

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

hr {
  margin: 2rem 0;
  border: 0;
  border-top: 1px solid var(--color-border-soft);
}

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

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

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

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

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

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

.section-compact {
  padding-top: clamp(40px, 6vw, 72px);
  padding-bottom: clamp(40px, 6vw, 72px);
}

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

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

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

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

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

.section-kicker,
.eyebrow {
  width: max-content;
  max-width: 100%;
  display: inline-flex;
  align-items: center;
  gap: 9px;
  min-height: 28px;
  padding: 0 11px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  color: var(--color-warn);
  background: var(--color-panel);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 520;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.eyebrow-indicator,
.status-dot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border: 1px solid var(--color-accent);
  border-radius: var(--radius-pill);
  background: var(--color-accent-dark);
}

.badge,
.tag {
  max-width: 100%;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-height: 28px;
  overflow: hidden;
  padding: 0 10px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  color: var(--color-text-muted);
  background: var(--color-panel);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  white-space: nowrap;
  text-overflow: ellipsis;
}

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

.button,
.btn,
.hero-button {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 0 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-none);
  color: var(--color-text);
  background: var(--color-panel);
  font-size: 14px;
  font-weight: 680;
  line-height: 1.2;
  cursor: pointer;
  transition:
    border-color var(--transition-fast),
    color var(--transition-fast),
    background-color var(--transition-fast),
    transform var(--transition-fast);
}

.button svg,
.btn svg,
.hero-button svg {
  width: 16px;
  height: 16px;
  flex: 0 0 auto;
}

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

.button-primary,
.btn-primary,
.hero-button-primary {
  border-color: var(--color-accent);
  color: var(--color-bg);
  background: var(--color-accent);
}

.button-primary:hover,
.button-primary:focus-visible,
.btn-primary:hover,
.btn-primary:focus-visible,
.hero-button-primary:hover,
.hero-button-primary:focus-visible {
  color: var(--color-accent);
  background: var(--color-accent-dark);
}

.button-secondary:hover,
.button-secondary:focus-visible,
.btn-secondary:hover,
.btn-secondary:focus-visible,
.hero-button-secondary:hover,
.hero-button-secondary:focus-visible {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.button[disabled],
.btn[disabled] {
  color: var(--color-text-dim);
  background: var(--color-panel);
  cursor: not-allowed;
  transform: none;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.panel,
.card {
  min-width: 0;
  border: 1px solid var(--color-border-soft);
  border-radius: var(--radius-none);
  background: var(--color-panel);
}

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

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

.card-body,
.panel-body {
  padding: clamp(20px, 3vw, 32px);
}

.grid {
  display: grid;
  gap: 20px;
}

.grid > * {
  min-width: 0;
}

.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));
}

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

.prose h2 {
  margin-top: 3.5rem;
  margin-bottom: 1.1rem;
}

.prose h3 {
  margin-top: 2.3rem;
  margin-bottom: 0.8rem;
}

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

.prose img {
  margin: 2rem auto;
  border: 1px solid var(--color-border-soft);
}

.prose blockquote {
  margin-inline: 0;
}

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

.header-inner {
  width: min(calc(100% - 56px), var(--page-width));
  height: 100%;
  margin-inline: auto;
  display: grid;
  grid-template-columns: 230px minmax(0, 1fr) auto;
  align-items: stretch;
  gap: 24px;
}

.brand {
  width: max-content;
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: var(--color-text);
}

.brand-mark {
  width: 31px;
  height: 31px;
  flex: 0 0 auto;
}

.brand-copy {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  white-space: nowrap;
}

.brand-en {
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 760;
  letter-spacing: -0.02em;
}

.brand-zh {
  color: var(--color-text-muted);
  font-size: 13px;
  font-weight: 450;
}

.primary-nav {
  display: flex;
  align-items: stretch;
  justify-content: center;
  gap: 4px;
}

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  padding: 0 12px;
  color: var(--color-text-muted);
  font-size: 13px;
  font-weight: 530;
  white-space: nowrap;
  transition: color var(--transition-fast), background-color var(--transition-fast);
}

.nav-link::after {
  position: absolute;
  right: 12px;
  bottom: -1px;
  left: 12px;
  height: 2px;
  content: "";
  background: var(--color-transparent);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform var(--transition-fast), background-color var(--transition-fast);
}

.nav-link:hover,
.nav-link:focus-visible {
  color: var(--color-text);
  background: var(--color-white-soft);
  outline: none;
}

.nav-link[aria-current="page"] {
  color: var(--color-text);
}

.nav-link[aria-current="page"]::after {
  background: var(--color-accent);
  transform: scaleX(1);
}

.header-tools {
  display: flex;
  align-items: center;
  gap: 8px;
}

.language-menu {
  position: relative;
}

.language-toggle,
.login-link,
.menu-toggle {
  min-height: 36px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-none);
  color: var(--color-text-muted);
  background: var(--color-transparent);
  font-size: 12px;
  font-weight: 560;
  white-space: nowrap;
}

.language-toggle {
  gap: 7px;
  padding: 0 11px;
  cursor: pointer;
}

.language-toggle svg {
  width: 14px;
  height: 14px;
}

.language-caret {
  color: var(--color-text-dim);
  font-size: 10px;
}

.login-link {
  padding: 0 17px;
  border-color: var(--color-accent-line);
  color: var(--color-accent);
  background: var(--color-panel);
}

.language-toggle:hover,
.language-toggle:focus-visible,
.login-link:hover,
.login-link:focus-visible,
.menu-toggle:hover,
.menu-toggle:focus-visible {
  border-color: var(--color-accent);
  color: var(--color-text);
}

.login-link:hover,
.login-link:focus-visible {
  color: var(--color-bg);
  background: var(--color-accent);
}

.language-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  z-index: 120;
  width: 158px;
  display: none;
  border: 1px solid var(--color-border);
  background: var(--color-panel-raised);
}

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

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

.language-dropdown a:hover,
.language-dropdown a:focus-visible,
.language-dropdown a[aria-current="true"] {
  color: var(--color-text);
  background: var(--color-white-soft);
}

.menu-toggle {
  min-width: 44px;
  min-height: 44px;
  display: none;
  padding: 0;
  cursor: pointer;
}

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  width: 19px;
  height: 1px;
  display: block;
  background: var(--color-text);
}

.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-drawer {
  display: none;
}

.nav-veil {
  display: none;
}

.site-footer {
  border-top: 1px solid var(--color-border-soft);
  background: var(--color-bg-deep);
}

.footer-main {
  display: grid;
  grid-template-columns: minmax(240px, 1.4fr) repeat(3, minmax(150px, 1fr));
  gap: clamp(32px, 5vw, 72px);
  padding-top: 64px;
  padding-bottom: 48px;
}

.footer-brand {
  max-width: 360px;
}

.footer-brand .brand {
  margin-bottom: 18px;
}

.footer-description {
  margin: 0;
  color: var(--color-text-muted);
  font-size: 14px;
}

.footer-heading {
  margin-bottom: 16px;
  color: var(--color-text);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

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

.footer-links li + li {
  margin-top: 8px;
}

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

.footer-links a:hover,
.footer-links a:focus-visible {
  color: var(--color-accent);
}

.footer-bottom {
  min-height: 62px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  border-top: 1px solid var(--color-border-soft);
  color: var(--color-text-dim);
  font-family: var(--font-mono);
  font-size: 11px;
}

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

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

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

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

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

@media (max-width: 1120px) {
  .header-inner {
    width: 100%;
    padding-inline: var(--gutter);
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: 14px;
  }

  .primary-nav {
    justify-content: flex-end;
  }

  .nav-link {
    padding-inline: 8px;
  }

  .nav-link::after {
    right: 8px;
    left: 8px;
  }

  .brand-zh {
    display: none;
  }
}

@media (max-width: 900px) {
  :root {
    --toc-top: 64px;
  }

  .site-header {
    height: 64px;
  }

  .header-inner {
    display: flex;
    align-items: center;
  }

  .primary-nav {
    display: none;
  }

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

  .language-menu {
    display: none;
  }

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

  .nav-veil {
    position: fixed;
    inset: 64px 0 0;
    z-index: 98;
    display: none;
    background: var(--color-overlay);
  }

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

  .mobile-drawer {
    position: fixed;
    top: 64px;
    right: 0;
    left: 0;
    z-index: 99;
    max-height: calc(100dvh - 64px);
    display: none;
    overflow-y: auto;
    overscroll-behavior: contain;
    border-bottom: 1px solid var(--color-border);
    background: var(--color-panel-raised);
  }

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

  .mobile-drawer a {
    width: 100%;
    min-height: 48px;
    display: flex;
    align-items: center;
    padding: 12px var(--gutter);
    border-bottom: 1px solid var(--color-border-soft);
    color: var(--color-text-muted);
    font-size: 14px;
  }

  .mobile-drawer a[aria-current="page"],
  .mobile-drawer a:hover,
  .mobile-drawer a:focus-visible {
    color: var(--color-text);
    background: var(--color-panel-soft);
  }

  .mobile-language-label {
    padding: 18px var(--gutter) 8px;
    color: var(--color-text-dim);
    font-family: var(--font-mono);
    font-size: 10px;
    letter-spacing: 0.1em;
    text-transform: uppercase;
  }

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

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

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

@media (max-width: 768px) {
  h1 {
    font-size: clamp(28px, 9vw, 40px);
    line-height: 1.12;
    letter-spacing: -0.018em;
  }

  h2 {
    font-size: clamp(1.75rem, 7vw, 2.4rem);
  }

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

  .section {
    padding-top: clamp(56px, 14vw, 80px);
    padding-bottom: clamp(56px, 14vw, 80px);
  }
}

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

  .nowrap-term {
    white-space: normal;
  }

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

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

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

  .brand-en {
    font-size: 16px;
  }

  .login-link {
    min-height: 44px;
    padding-inline: 13px;
  }

  .button-row {
    width: 100%;
  }

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

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

  .decor,
  .ambient,
  .hero-orb,
  .watermark {
    max-width: 100%;
  }

  .footer-main {
    grid-template-columns: minmax(0, 1fr);
    padding-top: 48px;
  }

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

  .footer-bottom {
    align-items: flex-start;
    flex-direction: column;
    padding-top: 20px;
    padding-bottom: 20px;
  }
}

@media (max-width: 380px) {
  .brand-copy {
    gap: 0;
  }

  .brand-zh {
    display: none;
  }

  .header-tools {
    gap: 5px;
  }

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

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

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

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