SOURCE

<div></div>

html,body { /*这里没用*/
                width: 100%;
                height: 100%;
                margin: 0;
                padding: 0;
            }
            div {
                width:100px;
                height:100px;
                color:turquoise;
                border:1px solid;
                border-radius:100px;
                outline:20px solid;
                outline-offset: -52px;;
                /*下面的只是垂直居中而已*/
                margin: 0 auto; 
                position: relative; 
                top: 50%; 
                margin-top: -60px;
            }