:root {
  --bg: white;
  --text: black;
  --muted: #666;
}

body.dark {
  --bg: #0f0f0f;
  --text: #ffffff;
  --muted: #aaaaaa;
}

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  transition: 0.3s;
}

.container {
  max-width: 700px;
  margin: 100px auto;
  padding: 20px;
}

h1 {
  font-size: 64px;
  margin: 0;
  letter-spacing: -2px;
}

.subtitle {
  font-size: 20px;
  color: var(--muted);
  margin-bottom: 40px;
}

h2 {
  font-size: 28px;
  margin-top: 40px;
}

p, li {
  font-size: 18px;
  line-height: 1.6;
}

button {
  margin-top: 40px;
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
}