:root {
  --bg: #fbfbf9;
  --fg: #1c1c19;
  --dim: #6c6c64;
  --rule: #e5e5de;
  --link: #14507c;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #151513;
    --fg: #eaeae4;
    --dim: #97978e;
    --rule: #2b2b27;
    --link: #97c0e8;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0 auto;
  padding: 4rem 1.5rem 3rem;
  max-width: 38rem;
  background: var(--bg);
  color: var(--fg);
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}

p {
  margin: 0 0 1rem;
}

a {
  color: var(--link);
  text-underline-offset: 2px;
}

a:focus-visible {
  outline: 2px solid var(--link);
  outline-offset: 3px;
  border-radius: 2px;
}

/* Header */

header {
  margin-bottom: 3.5rem;
}

h1 {
  margin: 0 0 0.6rem;
  font-size: 1.8125rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.15;
}

.sub {
  margin-bottom: 1.5rem;
  font-size: 1.0625rem;
  color: var(--dim);
}

.ask {
  margin-bottom: 1.25rem;
}

.facts {
  margin: 0 0 1.5rem;
  padding: 0;
  list-style: none;
  font-size: 0.9375rem;
  color: var(--dim);
}

.facts li::before {
  content: "";
  display: inline-block;
  width: 0.3rem;
  height: 0.3rem;
  margin-right: 0.55rem;
  vertical-align: 0.15em;
  border-radius: 50%;
  background: currentColor;
  opacity: 0.55;
}

.links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.5rem;
  margin: 0;
  font-size: 0.9375rem;
}

/* Sections */

section {
  margin-bottom: 3rem;
}

h2 {
  margin: 0 0 1.5rem;
  padding-bottom: 0.55rem;
  border-bottom: 1px solid var(--rule);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.11em;
  color: var(--dim);
}

article + article {
  margin-top: 2.25rem;
}

h3 {
  margin: 0;
  font-size: 1.0625rem;
  font-weight: 600;
  line-height: 1.3;
}

.meta {
  margin: 0.2rem 0 0.75rem;
  font-size: 0.875rem;
  color: var(--dim);
}

.meta span {
  padding: 0 0.3rem;
  opacity: 0.5;
}

/* Definition lists */

.courses,
.tools {
  margin: 0;
}

.courses {
  margin-top: 1rem;
}

.courses dt,
.tools dt {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--dim);
}

.courses dd,
.tools dd {
  margin: 0 0 0.85rem;
}

.courses dd:last-child,
.tools dd:last-child {
  margin-bottom: 0;
}

@media (min-width: 34rem) {
  .tools {
    display: grid;
    grid-template-columns: 9rem 1fr;
    gap: 0.7rem 1rem;
  }

  .tools dt {
    padding-top: 0.15rem;
  }

  .tools dd {
    margin-bottom: 0;
  }
}

/* Footer */

footer {
  padding-top: 1.75rem;
  border-top: 1px solid var(--rule);
  font-size: 0.9375rem;
}

footer p {
  margin: 0;
}

@media (max-width: 32rem) {
  body {
    padding: 2.75rem 1.25rem 2.5rem;
  }

  h1 {
    font-size: 1.5rem;
  }
}