Bootstrap 4

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css">
<button class="btn btn-link p-0">
  <div style="display:inline-block; background-color:#c2f5ff; width: 100px; height: 100px;">
  </div>
 </button>

CSS

body {
    margin: 10px;
}