:root {
  color-scheme: dark;
  --font-sans: "Inter", "SF Pro Text", "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  --bg-canvas: #060915;
  --bg-surface: rgba(16, 23, 41, 0.72);
  --bg-surface-strong: rgba(22, 30, 54, 0.86);
  --text-primary: #eef2ff;
  --text-secondary: #c6d0ee;
  --text-muted: #9ca8cd;

  --accent-1: #61dafb;
  --accent-2: #8f7dff;
  --accent-3: #40f8c5;

  --line-soft: rgba(143, 163, 219, 0.28);
  --glass-bg: rgba(17, 25, 45, 0.56);
  --glass-edge: rgba(183, 199, 245, 0.22);

  --shadow-sm: 0 8px 26px rgba(3, 9, 24, 0.34);

  --header-bg: rgba(6, 9, 21, 0.72);

  --radius-sm: 14px;
  --radius-md: 20px;

  --max-content: 880px;
}

[data-theme="light"] {
  color-scheme: light;

  --bg-canvas: #f5f7ff;
  --bg-surface: rgba(255, 255, 255, 0.78);
  --bg-surface-strong: rgba(255, 255, 255, 0.88);
  --text-primary: #151d34;
  --text-secondary: #364a72;
  --text-muted: #5f739c;

  --line-soft: rgba(63, 91, 140, 0.18);
  --glass-bg: rgba(255, 255, 255, 0.68);
  --glass-edge: rgba(70, 106, 168, 0.2);

  --shadow-sm: 0 8px 24px rgba(82, 102, 148, 0.14);

  --header-bg: rgba(245, 247, 255, 0.8);
}

* {
  box-sizing: border-box;
}

.skip-link {
  position: absolute;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  padding: 0.5rem 0.85rem;
  border-radius: 10px;
  background: var(--bg-surface-strong);
  border: 1px solid var(--line-soft);
  color: var(--text-primary);
  font-size: 0.85rem;
  font-weight: 600;
  transform: translateY(-160%);
  transition: transform 160ms ease;
}

.skip-link:focus-visible {
  transform: translateY(0);
  outline: 2px solid var(--accent-1);
  outline-offset: 2px;
}

.skip-link span[lang="zh"] {
  display: none;
}

body[data-lang="zh"] .skip-link span[lang="en"] {
  display: none;
}

body[data-lang="zh"] .skip-link span[lang="zh"] {
  display: inline;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 100px;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  background:
    radial-gradient(1200px 600px at 85% -10%, rgba(143, 125, 255, 0.14), transparent 60%),
    radial-gradient(900px 500px at 10% 0%, rgba(97, 218, 251, 0.12), transparent 55%),
    var(--bg-canvas);
  color: var(--text-primary);
  line-height: 1.7;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(14px);
  background: var(--header-bg);
  border-bottom: 1px solid var(--line-soft);
}

.nav-inner {
  max-width: var(--max-content);
  margin: 0 auto;
  padding: 0.9rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 700;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 10px;
  font-size: 0.85rem;
  font-weight: 800;
  color: #07101f;
  background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
  overflow: hidden;
}

.brand-mark img {
  width: 100%;
  height: 100%;
  border-radius: inherit;
  object-fit: cover;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.theme-toggle {
  position: relative;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  padding: 0;
  border: 1px solid var(--line-soft);
  border-radius: 999px;
  background: var(--glass-bg);
  color: var(--text-primary);
  font-size: 1rem;
  cursor: pointer;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.theme-toggle:hover {
  border-color: var(--accent-1);
  box-shadow: var(--shadow-sm);
}

.theme-toggle .theme-icon[hidden] {
  display: none;
}

.lang-toggle-group {
  display: inline-flex;
  padding: 4px;
  gap: 4px;
  border: 1px solid var(--line-soft);
  border-radius: 999px;
  background: var(--glass-bg);
}

.lang-toggle-group button {
  border: 0;
  cursor: pointer;
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  font: inherit;
  font-size: 0.85rem;
  color: var(--text-muted);
  background: transparent;
  transition: color 0.2s ease, background 0.2s ease;
}

.lang-toggle-group button.is-active {
  color: #07101f;
  background: linear-gradient(135deg, var(--accent-1), var(--accent-3));
  font-weight: 600;
}

main {
  max-width: var(--max-content);
  margin: 0 auto;
  padding: clamp(2rem, 6vw, 4rem) 1.25rem 4rem;
}

.kicker {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent-1);
  margin: 0 0 0.5rem;
}

h1 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  line-height: 1.25;
  margin: 0 0 0.75rem;
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.25rem;
  color: var(--text-muted);
  font-size: 0.92rem;
  margin-bottom: 2rem;
}

.policy-section {
  background: var(--bg-surface);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  padding: clamp(1.25rem, 3vw, 2rem);
  margin-bottom: 1.5rem;
}

.policy-section h2 {
  display: flex;
  align-items: baseline;
  gap: 0.65rem;
  font-size: 1.2rem;
  margin: 0 0 0.9rem;
}

.section-index {
  font-family: var(--font-mono);
  font-size: 0.85em;
  color: var(--accent-2);
}

.policy-section p,
.policy-section li {
  color: var(--text-secondary);
  font-size: 0.97rem;
}

.policy-section strong {
  color: var(--text-primary);
}

.policy-section a {
  color: var(--accent-1);
}

.policy-section ul,
.policy-section ol {
  padding-left: 1.35rem;
  margin: 0.5rem 0;
}

.policy-section li + li {
  margin-top: 0.4rem;
}

.perm-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  margin-top: 0.75rem;
}

.perm-table th,
.perm-table td {
  text-align: left;
  vertical-align: top;
  padding: 0.6rem 0.75rem;
  border-bottom: 1px solid var(--line-soft);
}

.perm-table th {
  color: var(--text-primary);
  font-weight: 600;
}

.perm-table td:first-child {
  font-family: var(--font-mono);
  font-size: 0.84rem;
  color: var(--accent-3);
  white-space: nowrap;
}

.callout {
  border-left: 3px solid var(--accent-1);
  background: rgba(97, 218, 251, 0.08);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 0.85rem 1.1rem;
  margin: 1rem 0;
}

.site-footer {
  border-top: 1px solid var(--line-soft);
  padding: 2rem 1.25rem 3rem;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.site-footer a {
  color: var(--accent-1);
}

/* Language visibility: default English */
.lang-block[data-lang="zh"] {
  display: none;
}

body[data-lang="zh"] .lang-block[data-lang="en"] {
  display: none;
}

body[data-lang="zh"] .lang-block[data-lang="zh"] {
  display: block;
}

@media (max-width: 640px) {
  .nav-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  .perm-table td:first-child {
    white-space: normal;
  }
}