:root {
  --bg-color: #ffffff;
  --text-color: #000000;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #121212;
    --text-color: #f0f0f0;
  }
}
body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  padding: 0;
}
header {
  text-align: center;
  padding: 2rem 1rem;
}
img.logo {
  max-width: 200px;
}
nav {
  text-align: center;
  margin-bottom: 2rem;
}
nav a {
  margin: 0 1rem;
  text-decoration: none;
  color: var(--text-color);
}
main {
  max-width: 800px;
  margin: auto;
  padding: 1rem;
}
footer {
  text-align: center;
  padding: 2rem 1rem;
  font-size: 0.9rem;
}