:root {
  --ink: #0f0f0f;
  --soft: #f3f3f3;
  --paper: #ffffff;
  --accent: #d6fd00;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

header,
main,
footer {
  width: min(760px, calc(100% - 2rem));
  margin: 0 auto;
}

header { padding: 1.25rem 0; }
main { padding: 2.5rem 0 4rem; }
footer {
  padding: 1.5rem 0;
  border-top: 1px solid var(--ink);
  font-size: 0.9rem;
}

nav { padding: 0.75rem 0; }

h1,
h2 { line-height: 1.2; }

h1 { font-size: clamp(2rem, 7vw, 3.25rem); }
h2 { margin-top: 2rem; }

section {
  margin-top: 2rem;
  padding-top: 0.25rem;
  border-top: 1px solid var(--soft);
}

a {
  color: var(--ink);
  text-decoration-color: var(--accent);
  text-decoration-thickness: 2px;
  text-underline-offset: 0.2em;
  transition: background-color 150ms ease;
}

a:hover,
a:focus-visible { background: var(--accent); }

.button {
  display: inline-block;
  margin: 0.5rem 0;
  padding: 0.65rem 1rem;
  border: 1px solid var(--ink);
  background: var(--accent);
  color: var(--ink);
  font-weight: bold;
  text-decoration: none;
  transition: background-color 150ms ease, color 150ms ease;
}

.button:hover,
.button:focus-visible {
  background: var(--ink);
  color: var(--paper);
}

@media (max-width: 520px) {
  nav { line-height: 2; }
  main { padding-top: 1.5rem; }
}

@media (prefers-reduced-motion: reduce) {
  a,
  .button { transition: none; }
}