@media only screen and (min-width: 800px) {
body {
    margin:auto;
    width: 30em;
}
}
body {
    margin:1em;
}
a {
    display: inline-block;
    border: 1px solid #ccc;
    background-color: #f9f9f9;
    color: #333;
    padding: 10px 20px;
    text-align: center;
    text-decoration: none;
    font-size: 16px;
    cursor: pointer;
    border-radius: 4px;
    width: 20em;
    margin:0.5em 0em;
  }
  
  a:hover {
    background-color: #e9e9e9;
  }