:root {
  color-scheme: light dark;
  --bg: #f2f2f7;
  --card: #ffffff;
  --text: #1c1c1e;
  --secondary: rgba(60, 60, 67, 0.72);
  --tertiary: rgba(60, 60, 67, 0.45);
  --separator: rgba(60, 60, 67, 0.18);
  --blue: #007aff;
  --tab: #8e8e93;
  --bar: rgba(249, 249, 249, 0.86);
  --fill: rgba(120, 120, 128, 0.12);
  --icon-bg: rgba(0, 122, 255, 0.12);
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.04), 0 8px 24px rgba(0, 0, 0, 0.04);
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "Segoe UI", sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --content: 42rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #000000;
    --card: #1c1c1e;
    --text: #f2f2f7;
    --secondary: rgba(235, 235, 245, 0.68);
    --tertiary: rgba(235, 235, 245, 0.4);
    --separator: rgba(84, 84, 88, 0.65);
    --blue: #0a84ff;
    --tab: #8e8e93;
    --bar: rgba(28, 28, 30, 0.86);
    --fill: rgba(120, 120, 128, 0.24);
    --icon-bg: rgba(10, 132, 255, 0.22);
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 17px;
  line-height: 1.47;
  -webkit-font-smoothing: antialiased;
}

html {
  scroll-padding-top: calc(52px + env(safe-area-inset-top));
  scroll-padding-bottom: calc(72px + env(safe-area-inset-bottom));
}

body {
  min-height: 100vh;
  padding-bottom: calc(72px + env(safe-area-inset-bottom));
}

a { color: var(--blue); }

.skip {
  position: absolute;
  left: 12px;
  top: -40px;
  background: var(--card);
  padding: 8px 12px;
  border-radius: 8px;
  z-index: 30;
}

.skip:focus { top: 12px; }

.frame {
  width: min(var(--content), calc(100% - 32px));
  margin: 0 auto;
}

.toolbar {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--bar);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 0.5px solid var(--separator);
}

.toolbar-row {
  width: min(var(--content), calc(100% - 32px));
  margin: 0 auto;
  min-height: 44px;
  display: flex;
  align-items: center;
  padding-top: env(safe-area-inset-top);
}

.back {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  margin-left: -6px;
  color: var(--blue);
  text-decoration: none;
  font-size: 17px;
}

.back svg { width: 12px; height: 20px; display: block; }

.title-block {
  padding: 18px 0 8px;
}

.title-block h1 {
  margin: 0;
  font-size: 34px;
  line-height: 1.15;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.lede, .updated {
  margin: 6px 0 0;
  color: var(--secondary);
  font-size: 15px;
}

.library {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 8px 0 24px;
}

.card {
  display: grid;
  grid-template-columns: 48px 1fr auto;
  gap: 14px;
  align-items: center;
  padding: 16px;
  background: var(--card);
  border-radius: 16px;
  box-shadow: var(--shadow);
  color: inherit;
  text-decoration: none;
}

.card:active { opacity: 0.72; }

.card:focus-visible, .tab:focus-visible, .back:focus-visible, .segment a:focus-visible {
  outline: 3px solid var(--blue);
  outline-offset: 2px;
}

.card-icon, .tab svg {
  color: var(--blue);
}

.card-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  background: var(--icon-bg);
  display: grid;
  place-items: center;
}

.card-icon svg { width: 26px; height: 26px; }

.card-title {
  display: block;
  font-size: 17px;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.card-summary, .card-meta {
  display: block;
  color: var(--secondary);
  font-size: 13px;
  line-height: 1.35;
}

.card-meta { margin-top: 4px; color: var(--tertiary); }

.chevron {
  color: var(--tertiary);
  font-size: 22px;
  line-height: 1;
}

.status {
  color: var(--secondary);
  font-size: 15px;
}

.segment {
  display: flex;
  gap: 2px;
  padding: 2px;
  margin: 4px 0 16px;
  background: var(--fill);
  border-radius: 9px;
}

.segment a {
  flex: 1;
  text-align: center;
  text-decoration: none;
  color: var(--text);
  font-size: 13px;
  font-weight: 590;
  padding: 6px 8px;
  border-radius: 7px;
}

.segment a[aria-current="page"] {
  background: var(--card);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

.policy h2 {
  margin: 32px 0 8px;
  font-size: 22px;
  line-height: 1.2;
  letter-spacing: -0.015em;
  scroll-margin-top: calc(64px + env(safe-area-inset-top));
}

.policy h3 {
  margin: 22px 0 6px;
  font-size: 17px;
}

.policy p { margin: 0 0 12px; }

.policy ul, .policy ol {
  margin: 0 0 14px;
  padding-left: 1.2em;
}

.policy li { margin: 6px 0; }

.policy code {
  font-family: var(--mono);
  font-size: 0.86em;
}

.toc {
  margin: 8px 0 4px;
  padding: 4px 0;
}

.toc a {
  display: block;
  padding: 8px 0;
  text-decoration: none;
  border-top: 0.5px solid var(--separator);
  font-size: 15px;
}

.toc a:first-child { border-top: none; }

.spec, .note {
  background: var(--card);
  border-radius: 12px;
  overflow: hidden;
  margin: 12px 0 16px;
}

.spec div {
  display: grid;
  grid-template-columns: minmax(7.5rem, 38%) 1fr;
  gap: 12px;
  padding: 11px 16px;
  border-top: 0.5px solid var(--separator);
}

.spec div:first-child { border-top: none; }

.spec dt {
  margin: 0;
  color: var(--secondary);
  font-weight: 400;
}

.spec dd {
  margin: 0;
  font-weight: 600;
  text-align: right;
  overflow-wrap: break-word;
}

@media (max-width: 520px) {
  .spec div {
    grid-template-columns: 1fr;
    gap: 2px;
  }

  .spec dd { text-align: left; }
}

.note { padding: 14px 16px; }
.note p:last-child { margin-bottom: 0; }

.tab-bar:empty { display: none; }

.tab-bar {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 20;
  display: flex;
  justify-content: space-around;
  height: calc(49px + env(safe-area-inset-bottom));
  padding: 0 8px env(safe-area-inset-bottom);
  background: var(--bar);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  backdrop-filter: saturate(180%) blur(20px);
  border-top: 0.5px solid var(--separator);
}

.tab {
  flex: 1;
  max-width: 96px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1px;
  color: var(--tab);
  text-decoration: none;
  font-size: 10px;
  line-height: 1.15;
  letter-spacing: 0.01em;
}

.tab svg { width: 25px; height: 25px; color: inherit; }

.tab[aria-current="page"] { color: var(--blue); }

@media (min-width: 720px) {
  .title-block { padding-top: 28px; }
}

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

@media print {
  body { background: #fff; color: #000; padding: 0; }
  .toolbar, .tab-bar, .skip, .back { display: none; }
  a { color: #000; }
}