#container{
        display:table-cell; 
        width:300px; 
        height:300px; 
        vertical-align:middle; 
        border:1px solid #ccc; 
        border-radius:20px;
        text-align:center; 
}
#cell{
        margin: 0 auto; 
        width:100px; 
        height:100px; 
        border:1px solid red; 
        border-radius:10px;
 }