:root {
  --bg-color: #f4f4f9;
  --text-color: #333;
  --primary-color: #007bff;
  --container-width: 800px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #1e1e1e;
    --text-color: #e0e0e0;
    --primary-color: #66b2ff;
  }
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--bg-color);
  margin: 0;
  padding: 0;
}

header {
  background: var(--primary-color);
  color: #fff;
  padding: 2rem 0;
  text-align: center;
}

header h1 {
  margin: 0;
}

.container {
  max-width: var(--container-width);
  margin: 2rem auto;
  padding: 0 1rem;
}

.card {
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(0, 0, 0, 0.1);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  border-radius: 8px;
}

@media (prefers-color-scheme: dark) {
  .card {
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.1);
  }
}

a {
  color: var(--primary-color);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

footer {
  text-align: center;
  padding: 2rem 0;
  font-size: 0.9em;
  opacity: 0.8;
}

.btn {
  display: inline-block;
  background: var(--primary-color);
  color: #fff;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  text-decoration: none;
  margin-top: 1rem;
}

.btn:hover {
  opacity: 0.9;
  text-decoration: none;
}