✅ style.css (simple design)

```css
body {
  font-family: Arial, sans-serif;
  background: #f4f7fc;
  margin: 0;
  padding: 0;
  text-align: center;
}

header {
  background: #2c3e50;
  color: white;
  padding: 40px 20px;
}

.btn {
  display: inline-block;
  background: #27ae60;
  color: white;
  padding: 10px 20px;
  margin: 10px;
  text-decoration: none;
  border-radius: 5px;
}

.btn:hover {
 background: #2ecc71;
}

.features {
  padding: 30px;
}

.features ul {
  list-style: none;
  padding: 0;
}

.features li {
  margin: 10px 0;
  font-size: 18px;
}

footer {
  background: #34495e;
  color: white;
  padding: 15px;
  position: fixed;
  bottom: 0;
  width: 100%;
}