body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 20px;
  background: #f5f5f5;
}
header {
  background: #2A9D8F;
  color: #fff;
  padding: 10px 20px;
}
button {
  padding: 10px;
  margin-top: 10px;
  cursor: pointer;
}