Edit in JSFiddle

<div class='circle'></div>
<div class='circle rounded'></div>

.circle{
    width: 100px;
    height: 100px;
    margin: 1em;
    background: #ccc;
    border: 3px dotted #333;
    border-radius: 50%;
}

.rounded{
    border-radius: 20%;
}