body {
  font-family: Arial, sans-serif;
  text-align: center;
  margin: 0;
  padding: 0;
}

nav {
  background: #333;
  color: #fff;
  padding: 10px;
}

nav a {
  color: #fff;
  margin: 0 10px;
  text-decoration: none;
}

main {
  margin: 50px auto;
  max-width: 600px;
}

.button {
  display: inline-block;
  padding: 15px 30px;
  margin-top: 20px;
  background: #0074D9;
  color: #fff;
  text-decoration: none;
  border-radius: 5px;
}

.button.disabled {
  background: #999;
  pointer-events: none;
  cursor: default;
}

.ads {
  margin: 30px 0;
  border: 2px dashed #ddd;
  padding: 20px;
}