.circle {
background-color:#fff;
border:1px solid red;
height:100px;
border-radius:50%;
-moz-border-radius:50%;
-webkit-border-radius:50%;
width:100px;
}
<div class="circle"></div>
#div2{
width: 150px;
height: 150px;
border: 3px solid #05ffb0;
border-radius: 50%;
padding: 20px;
text-align: center;
}