:root {
  color-scheme: light dark;
  --bg: #f5f5f7;
  --fg: #1d1d1f;
  --muted: #6e6e73;
  --card: #ffffff;
  --border: rgba(0, 0, 0, 0.08);
  --accent: #0071e3;
  --accent-fg: #ffffff;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101014;
    --fg: #f5f5f7;
    --muted: #98989d;
    --card: #1b1b20;
    --border: rgba(255, 255, 255, 0.1);
    --accent: #2997ff;
    --accent-fg: #0b0b0e;
  }
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
  width: 100%;
  max-width: 40rem;
  margin: 0 auto;
  padding: 4.5rem 1.5rem 2rem;
  text-align: center;
}

.app-icon {
  width: 112px;
  height: 112px;
}

h1 {
  font-size: 2.6rem;
  letter-spacing: -0.02em;
  margin-top: 0.5rem;
}

.tagline {
  font-size: 1.2rem;
  font-weight: 600;
  margin-top: 0.15rem;
}

.subtagline {
  margin-top: 0.6rem;
  color: var(--muted);
  font-size: 0.95rem;
}

.cta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
  margin-top: 1.5rem;
}

.button {
  display: inline-block;
  padding: 0.6rem 1.5rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--fg);
  text-decoration: none;
  font-weight: 600;
  transition: filter 0.15s ease, transform 0.15s ease;
}

.button:hover {
  filter: brightness(1.08);
  transform: translateY(-1px);
}

.button.primary {
  background: var(--accent);
  border-color: transparent;
  color: var(--accent-fg);
}

.fineprint {
  margin-top: 0.9rem;
  color: var(--muted);
  font-size: 0.85rem;
}

.viz-wrap {
  margin-top: 2.5rem;
}

#viz {
  max-width: 100%;
  touch-action: manipulation;
}

.viz-toggle {
  display: inline-flex;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px;
  margin-bottom: 1.2rem;
}

.viz-toggle button {
  border: none;
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.35rem 1.1rem;
  border-radius: 999px;
  cursor: pointer;
}

.viz-toggle button.active {
  background: var(--accent);
  color: var(--accent-fg);
}

.status {
  color: var(--fg);
  font-size: 0.9rem;
  min-height: 1.4em;
  margin-top: 0.5rem;
  font-variant-numeric: tabular-nums;
}

/* Prose pages (privacy, etc.): single column, left-aligned at every width. */
main.prose {
  max-width: 40rem;
  display: block;
  text-align: left;
  padding: 4.5rem 1.5rem 2rem;
}

main.prose h1 {
  margin-bottom: 0.25rem;
}

main.prose h2 {
  font-size: 1.15rem;
  margin-top: 1.75rem;
}

main.prose p {
  margin-top: 0.5rem;
}

main.prose .updated {
  color: var(--muted);
  font-size: 0.85rem;
}

footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.8rem;
  padding: 1.5rem;
}

footer a {
  color: inherit;
}

/* Two-column split on wide screens: intro left, visualization right. */
@media (min-width: 60rem) {
  main {
    max-width: 66rem;
    padding: 2rem 1.5rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
    text-align: left;
  }

  .cta {
    justify-content: flex-start;
  }

  .viz-wrap {
    margin-top: 0;
    text-align: center;
  }
}