:root {
  color-scheme: light dark;
  --background: #f5f7fa;
  --surface: #ffffff;
  --text: #18202a;
  --secondary: #5e6a78;
  --accent: #2878d0;
  --border: #dce2e9;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", sans-serif;
  line-height: 1.8;
}

main {
  width: min(760px, calc(100% - 32px));
  margin: 48px auto;
  padding: clamp(24px, 5vw, 48px);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 20px;
  box-shadow: 0 12px 40px rgb(20 35 55 / 8%);
}

h1, h2 { line-height: 1.4; }
h1 { margin-top: 0; font-size: clamp(1.8rem, 5vw, 2.5rem); }
h2 { margin-top: 2.2em; font-size: 1.25rem; }
a { color: var(--accent); }
ul, ol { padding-left: 1.4em; }
.lead { color: var(--secondary); font-size: 1.05rem; }
.card {
  display: block;
  margin: 20px 0;
  padding: 20px;
  color: inherit;
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 14px;
}
.card:hover { border-color: var(--accent); }
.card strong { display: block; font-size: 1.1rem; }
.card span, .meta { color: var(--secondary); }
nav { margin-bottom: 28px; }
footer {
  margin-top: 48px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  color: var(--secondary);
  font-size: .9rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --background: #101419;
    --surface: #171d24;
    --text: #edf2f7;
    --secondary: #aab5c0;
    --accent: #69aef7;
    --border: #323b46;
  }
}