body {
  background-color: lightgreen;
  font-size: 2em;
  text-align: center;
}
button {
    font-size: 5em;
    color: darkred;
    border: double;
    margin-top: 20px;
    box-shadow: 5px 5px 10px rgba(0, 0, 0, 0.2);
    padding: 15px 30px;
    transition: all 0.3s ease-in-out;
    border-radius: 25px;
     background-image: radial-gradient(circle, black);    
    display: block;
margin: 0 auto; 
 border-width: 20px;
}