* {
  box-sizing: border-box;
}
html,
body {
  margin: 0;
  padding: 0;
  font-family:
    system-ui,
    -apple-system,
    Segoe UI,
    Roboto,
    Helvetica,
    Arial,
    sans-serif;
}
header {
  background: #0a2540;
  color: #fff;
  padding: 1rem;
}
main {
  padding: 1rem;
  max-width: 800px;
  margin: 0 auto;
}
section {
  background: #f6f8fa;
  padding: 1rem;
  border-radius: 8px;
  border: 1px solid #e1e4e8;
}