:root {
  color-scheme: light;
  --text: #111827;
  --muted: #4b5563;
  --link: #0645ad;
  --border: #d1d5db;
  --background: #ffffff;
  --soft: #f3f4f6;
}

html {
  font-size: 100%;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.65;
  color: var(--text);
  background: var(--background);
}

.wrapper {
  max-width: 58rem;
  margin: 0 auto;
  padding: 2rem 1.25rem 3rem;
}

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

a:focus {
  outline: 3px solid #111827;
  outline-offset: 2px;
}

h1,
h2,
h3 {
  line-height: 1.25;
  margin: 2rem 0 0.75rem;
}

h1 {
  font-size: 2rem;
  margin-top: 0.5rem;
}

h2 {
  font-size: 1.45rem;
  border-top: 1px solid var(--border);
  padding-top: 1.25rem;
}

p {
  margin: 0 0 1rem;
}

ul,
ol {
  margin: 0 0 1.25rem 1.5rem;
  padding: 0;
}

li {
  margin: 0.25rem 0;
}

nav {
  margin: 1rem 0 2rem;
  padding: 1rem;
  background: var(--soft);
  border: 1px solid var(--border);
}

nav ul {
  margin-bottom: 0;
}

.topic-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: space-between;
}

.source-note {
  color: var(--muted);
  font-size: 0.95rem;
}