:root {
  --bg: #f4f6f8;
  --surface: #ffffff;
  --text: #17212b;
  --muted: #4e5d6c;
  --border: #d5dde5;
  --accent: #1166cc;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: linear-gradient(180deg, #eef3f8 0%, var(--bg) 35%, var(--bg) 100%);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.5;
}

.page-header,
main,
.page-footer {
  width: min(920px, calc(100% - 2rem));
  margin: 0 auto;
}

.page-header {
  padding: 2.5rem 0 1rem;
}

.eyebrow {
  margin: 0 0 0.5rem;
  color: var(--muted);
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  line-height: 1.2;
}

h2 {
  font-size: clamp(1.2rem, 2.5vw, 1.5rem);
  line-height: 1.25;
}

h3 {
  font-size: 1.05rem;
  line-height: 1.3;
}

p,
li {
  max-width: 75ch;
}

.lead {
  margin: 1rem 0 0.75rem;
  color: var(--muted);
  max-width: 70ch;
}

.meta {
  margin: 0;
  font-size: 0.95rem;
}

main {
  padding-bottom: 2rem;
}

.toc,
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1rem 1.25rem;
}

.toc {
  margin-bottom: 1rem;
}

.toc h2 {
  margin-top: 0;
}

.toc ul {
  margin: 0;
  padding-left: 1.1rem;
}

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

a {
  color: var(--accent);
  text-underline-offset: 0.16em;
}

a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

.card {
  margin-bottom: 1rem;
}

.card h2 {
  margin-top: 0;
}

.page-footer {
  padding: 0 0 2rem;
  color: var(--muted);
}

@media (max-width: 640px) {
  .page-header {
    padding-top: 1.75rem;
  }

  .toc,
  .card {
    padding: 0.95rem 1rem;
  }

  body {
    line-height: 1.55;
  }
}