:root {
  color-scheme: dark;
  --bg: #12161a;
  --ink: #e7eef2;
  --muted: #93a4ad;
  --line: #2a3840;
  --accent: #7dcea0;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font: 16px/1.5 "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--ink);
}
.top, main, footer { width: min(960px, calc(100% - 32px)); margin: 0 auto; }
.top { display: flex; justify-content: space-between; align-items: center; padding: 20px 0; }
.mark { color: var(--ink); font-weight: 700; text-decoration: none; }
nav a { color: var(--muted); margin-left: 16px; }
.hero { padding: 48px 0 24px; }
.eyebrow { color: var(--accent); letter-spacing: 0.08em; text-transform: uppercase; font-size: 12px; }
h1 { font-size: 40px; line-height: 1.15; margin: 8px 0; }
.lead { color: var(--muted); max-width: 62ch; }
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
article, ol { border: 1px solid var(--line); padding: 16px; }
.preview {
  height: 120px;
  margin: 0 0 12px;
  background:
    radial-gradient(circle at 20% 40%, #7dcea0 0 2px, transparent 3px),
    radial-gradient(circle at 40% 60%, #d8efe2 0 1px, transparent 2px),
    radial-gradient(circle at 70% 30%, #7dcea0 0 2px, transparent 3px),
    linear-gradient(#1b2429, #1b2429);
}
footer { color: var(--muted); padding: 32px 0 48px; }
@media (max-width: 800px) {
  .grid { grid-template-columns: 1fr; }
  h1 { font-size: 32px; }
}