:root {
  color-scheme: light dark;
  --bg: #0b1020;
  --fg: #e8eefc;
  --muted: #9aa8c7;
  --accent: #5b8cff;
  --card: #141b2f;
  --line: #243049;
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f6f8fc;
    --fg: #152038;
    --muted: #5b6b88;
    --accent: #2f5fdb;
    --card: #ffffff;
    --line: #d7deee;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.55;
}

header, main, footer {
  max-width: 720px;
  margin: 0 auto;
  padding: 1.25rem 1.25rem;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  border-bottom: 1px solid var(--line);
}

.brand {
  margin: 0;
  font-weight: 700;
  letter-spacing: 0.02em;
}

nav {
  display: flex;
  gap: 0.9rem;
  flex-wrap: wrap;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

h1 { font-size: 1.75rem; margin: 0.2rem 0 0.8rem; }
h2 { font-size: 1.1rem; margin-top: 1.4rem; }

section {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.9rem 1rem 1rem;
  margin: 1rem 0;
}

.muted { color: var(--muted); }
hr { border: 0; border-top: 1px solid var(--line); margin: 2rem 0; }

footer {
  color: var(--muted);
  font-size: 0.9rem;
  border-top: 1px solid var(--line);
}