:root {
  --color-bg: #F5F8F8;
  --color-panel: #FFFFFF;
  --color-panel-muted: #EDF1F1;
  --color-border: #DDE3E3;
  --color-accent: #149E52;
  --color-accent-dark: #0C7A3E;
  --color-text: #1B2420;
  --color-text-muted: #5A6662;
  --color-success: #128A4C;
  --color-warning: #B9860F;
  --color-error: #C24141;
  --color-flag-red: #D0362D;
  --color-flag-blue: #2A4B8D;
  --color-flag-navy: #3C3B6E;
  --color-focus: #0C7A3E;
  --color-overlay: color-mix(in srgb, var(--color-text) 34%, transparent);
  --color-accent-soft: color-mix(in srgb, var(--color-accent) 8%, var(--color-panel));
  --color-accent-border: color-mix(in srgb, var(--color-accent) 28%, var(--color-border));
  --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-large: 14px;
  --radius-medium: 10px;
  --radius-small: 7px;
  --radius-pill: 999px;
  --gutter: clamp(16px, 3vw, 32px);
  --content-width: 1252px;
  --reading-width: 760px;
  --header-height: 66px;
  --section-space: clamp(68px, 9vw, 120px);
  --shadow-soft: 0 1px 3px color-mix(in srgb, var(--color-text) 7%, transparent);
  --shadow-card: 0 8px 24px -18px color-mix(in srgb, var(--color-text) 28%, transparent);
  --shadow-device:
    0 1px 2px color-mix(in srgb, var(--color-text) 9%, transparent),
    0 6px 14px -4px color-mix(in srgb, var(--color-text) 10%, transparent),
    0 42px 72px -28px color-mix(in srgb, var(--color-text) 26%, transparent);
  --transition-fast: 160ms ease;
  --transition-normal: 420ms cubic-bezier(.2, .7, .2, 1);
  --toc-offset: 96px;
}

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

html {
  min-width: 320px;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
}

html.nav-open {
  overflow: hidden;
}

body {
  min-width: 320px;
  margin: 0;
  overflow-x: clip;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 15px;
  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 {
  max-width: 100%;
}

img {
  display: block;
  height: auto;
}

svg {
  flex-shrink: 0;
}

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

button,
summary {
  cursor: pointer;
}

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

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

p:last-child,
ul:last-child,
ol:last-child {
  margin-bottom: 0;
}

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

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

:not(pre) > code {
  overflow-wrap: anywhere;
  padding: .12em .38em;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-small);
  background: var(--color-panel-muted);
  font-size: .9em;
}

pre {
  max-width: 100%;
  overflow-x: auto;
  padding: 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-medium);
  background: var(--color-text);
  color: var(--color-panel);
  -webkit-overflow-scrolling: touch;
}

pre code {
  white-space: pre;
}

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

h1 {
  margin-bottom: 24px;
  font-size: clamp(52px, 5vw, 68px);
  font-weight: 900;
  letter-spacing: -.018em;
  line-height: 1.1;
}

h2 {
  margin-bottom: 20px;
  font-size: clamp(34px, 4vw, 50px);
  font-weight: 900;
  letter-spacing: -.015em;
  line-height: 1.14;
}

h3 {
  margin-bottom: 12px;
  font-size: clamp(21px, 2.2vw, 28px);
  font-weight: 800;
  line-height: 1.25;
}

h4 {
  margin-bottom: 8px;
  font-size: 17px;
  font-weight: 800;
}

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

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

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

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

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

.reading {
  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);
  overflow-x: clip;
}

.section-panel {
  background: var(--color-panel);
  border-block: 1px solid var(--color-border);
}

.section-heading {
  max-width: 780px;
  margin-bottom: clamp(30px, 5vw, 54px);
}

.eyebrow,
.kicker {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  max-width: 100%;
  margin: 0 0 20px;
  padding: 5px 14px;
  border: 1px solid var(--color-accent-border);
  border-radius: var(--radius-pill);
  background: var(--color-accent-soft);
  color: var(--color-accent-dark);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
}

.status-dot {
  width: 7px;
  height: 7px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--color-success);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-success) 18%, transparent);
}

.badge,
.fact-pill,
.tag {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  gap: 6px;
  max-width: 100%;
  padding: 5px 11px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-pill);
  background: var(--color-panel);
  color: var(--color-text-muted);
  font-size: 12px;
  font-weight: 700;
  overflow-wrap: anywhere;
}

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

.panel,
.card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-large);
  background: var(--color-panel);
  box-shadow: var(--shadow-card);
}

.panel {
  padding: clamp(22px, 4vw, 40px);
}

.card {
  padding: 24px;
}

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

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

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

.btn {
  display: inline-flex;
  min-width: 24px;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 30px;
  border: 1.5px solid transparent;
  border-radius: var(--radius-medium);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 750;
  line-height: 1;
  text-align: center;
  transition: background var(--transition-fast), border-color var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--color-accent);
  color: var(--color-panel);
  box-shadow: 0 8px 20px -8px color-mix(in srgb, var(--color-accent) 55%, transparent);
}

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

.btn-secondary {
  border-color: var(--color-border);
  background: var(--color-panel);
  color: var(--color-text);
  box-shadow: var(--shadow-soft);
}

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

.btn-small {
  min-height: 38px;
  padding: 10px 17px;
  font-size: 13px;
}

button:disabled,
.btn[aria-disabled="true"] {
  cursor: not-allowed;
  opacity: .52;
  transform: none;
}

a:focus-visible,
button:focus-visible,
summary:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible,
[role="tab"]:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
}

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

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

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

.site-topbar {
  position: relative;
  z-index: 50;
  border-bottom: 1px solid var(--color-border);
  background: color-mix(in srgb, var(--color-bg) 86%, var(--color-panel));
}

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

.site-brand {
  display: inline-flex;
  flex: none;
  align-items: center;
  gap: 10px;
  min-height: 44px;
  font-family: var(--font-display);
}

.site-brand img {
  width: 30px;
  height: 30px;
}

.site-brand-main {
  font-size: 19px;
  font-weight: 900;
  letter-spacing: -.01em;
}

.site-brand-local {
  color: var(--color-text-muted);
  font-size: 15px;
  font-weight: 600;
}

.desktop-nav {
  display: flex;
  align-items: center;
  margin-inline: auto;
  color: var(--color-text-muted);
  font-size: 14px;
}

.desktop-nav a {
  display: inline-flex;
  min-height: 36px;
  align-items: center;
  padding: 4px 2px;
  font-weight: 550;
}

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

.desktop-nav a.is-active {
  font-weight: 750;
}

.nav-separator {
  margin-inline: 12px;
  color: var(--color-border);
  font-weight: 800;
  user-select: none;
}

.header-tools {
  display: flex;
  flex: none;
  align-items: center;
  gap: 10px;
}

.language-control {
  position: relative;
}

.language-button {
  display: inline-flex;
  min-width: 44px;
  min-height: 44px;
  align-items: center;
  gap: 5px;
  padding: 8px;
  border: 0;
  background: transparent;
  color: var(--color-text-muted);
  font-size: 13px;
}

.language-menu {
  position: absolute;
  top: calc(100% + 7px);
  right: 0;
  z-index: 70;
  display: none;
  width: 156px;
  padding: 7px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-medium);
  background: var(--color-panel);
  box-shadow: var(--shadow-device);
}

.language-control.is-open .language-menu {
  display: grid;
}

.language-menu a {
  display: flex;
  min-height: 40px;
  align-items: center;
  padding: 8px 10px;
  border-radius: var(--radius-small);
  color: var(--color-text-muted);
  font-size: 13px;
}

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

.header-login {
  min-height: 40px;
  padding: 10px 20px;
}

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

.menu-toggle-lines,
.menu-toggle-lines::before,
.menu-toggle-lines::after {
  width: 19px;
  height: 2px;
  border-radius: var(--radius-pill);
  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-nav {
  position: absolute;
  top: var(--header-height);
  right: 0;
  left: 0;
  z-index: 65;
  display: none;
  max-height: calc(100dvh - var(--header-height));
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 10px var(--gutter) 20px;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-panel);
}

.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-border);
  color: var(--color-text-muted);
  font-weight: 650;
}

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

.mobile-language-list {
  display: grid;
  margin-top: 12px;
}

.mobile-language-list a {
  font-size: 13px;
}

.menu-veil {
  position: fixed;
  inset: var(--header-height) 0 0;
  z-index: 40;
  display: none;
  border: 0;
  background: var(--color-overlay);
}

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

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

.footer-main {
  display: grid;
  grid-template-columns: 1.25fr 1fr 1fr 1fr;
  gap: clamp(26px, 5vw, 64px);
  padding-top: 64px;
  padding-bottom: 46px;
}

.footer-brand p {
  max-width: 340px;
  color: var(--color-text-muted);
}

.footer-title {
  margin-bottom: 15px;
  font-size: 13px;
  font-weight: 850;
}

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

.footer-links a {
  width: fit-content;
  min-height: 28px;
  color: var(--color-text-muted);
  font-size: 13px;
}

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

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding-top: 20px;
  padding-bottom: 24px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
  font-size: 12px;
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

@media (max-width: 1040px) {
  .desktop-nav {
    display: none;
  }

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

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

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

@media (max-width: 768px) {
  h1 {
    font-size: clamp(34px, 9.5vw, 40px);
    letter-spacing: -.015em;
  }

  h2 {
    font-size: clamp(28px, 8vw, 36px);
  }

  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }

  .language-control {
    display: none;
  }
}

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

  .site-topbar-inner {
    gap: 8px;
  }

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

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

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

  .card,
  .panel {
    padding: 19px;
  }

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

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

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

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0s !important;
    animation-duration: 0s !important;
  }

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