:root {
  color-scheme: light dark;
  --background: #f6f8fc;
  --surface: #ffffff;
  --text: #18212f;
  --muted: #5f6b7c;
  --border: #d9e0ea;
  --accent: #2563eb;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #09111d;
    --surface: #101a28;
    --text: #eef4ff;
    --muted: #a7b3c6;
    --border: #2a3749;
    --accent: #75a7ff;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font-family: Inter, ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 17px;
  line-height: 1.65;
}

header {
  position: sticky;
  top: 0;
  z-index: 2;
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  backdrop-filter: blur(14px);
}

.bar, main, footer {
  width: min(900px, calc(100% - 40px));
  margin: 0 auto;
}

.bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  min-height: 74px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-size: 24px;
  font-weight: 800;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 32px;
  border: 2px solid var(--accent);
  border-radius: 8px;
  color: var(--accent);
  font-size: 20px;
}

nav { display: flex; gap: 16px; }

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

nav a {
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
}

main {
  margin-top: 42px;
  margin-bottom: 42px;
  padding: clamp(26px, 5vw, 58px);
  border: 1px solid var(--border);
  border-radius: 22px;
  background: var(--surface);
  box-shadow: 0 20px 55px rgb(0 0 0 / 8%);
}

h1 {
  margin: 0;
  font-size: clamp(34px, 6vw, 54px);
  line-height: 1.1;
  letter-spacing: -0.04em;
}

.effective {
  margin: 12px 0 38px;
  color: var(--muted);
  font-weight: 650;
}

h2 {
  margin: 34px 0 10px;
  font-size: 24px;
  line-height: 1.25;
}

p, li { color: var(--text); }

ul { padding-left: 24px; }

footer {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding: 0 0 42px;
  color: var(--muted);
  font-size: 14px;
}

@media (max-width: 640px) {
  .bar, main, footer { width: min(100% - 24px, 900px); }
  .bar { align-items: flex-start; flex-direction: column; justify-content: center; padding: 14px 0; }
  nav { flex-wrap: wrap; }
  main { margin-top: 18px; padding: 24px 20px; border-radius: 16px; }
  footer { flex-direction: column; }
}