Edit in JSFiddle

body,
html{
    height:100%;
    width: 100%; /* needed for FF */
    display: box;
    box-orient:horizontal;
    box-pack:center;
    box-align:center;
    
    display: -webkit-box;
    -webkit-box-orient: horizontal;
    -webkit-box-pack: center;
    -webkit-box-align: center; 
    
    display: -moz-box;
    -moz-box-orient:horizontal;
    -moz-box-pack:center;
    -moz-box-align:center;
    
    display:-ms-flexbox;
    -ms-flex-pack:center;
    -ms-flex-align:center;
}


div{
    width: 100px;
    height: 100px;
    background-color: #e9573f;
    -webkit-border-radius: 3px;
    -moz-border-radius: 3px;
    -ms-border-radius: 3px;
    -o-border-radius: 3px;
}
<div></div>