button, a {
    display: inline-block;
    background-color: #666;
    color: #fff;
    padding: 10px 20px;
    border: none;
    text-decoration: none;
    font-size: 16px;
    margin: 5px;
    cursor: pointer;
    
  }
body {
    font-family: sans-serif;
    
}
ul{
    list-style: none;
   
}
html, body {
    height: 100%;
}

html {
    display: table;
    margin: auto;
}

body {
    display: table-cell;
    vertical-align: middle;
}