how to create a circle with css

1
2    #circle {
3      width: 100px;
4      height: 100px;
5      background: red;
6      border-radius: 50%
7    }
8  

1#circle {
2  width: 100px;
3  height: 100px;
4  background: red;
5  border-radius: 50%
6}
7

1#circle {
2  width: 100px;
3  height: 100px;
4  background: red;
5  border-radius: 50%
6}

1<div id="circle">
2</div>
3
4#circle {
5    width: 100px;
6    height: 100px;
7    background: red;
8    border-radius: 50%
9}

1span {
2    display: block;
3    height: 60px;
4    width: 60px;
5    line-height: 60px;
6
7    -moz-border-radius: 30px; /* or 50% */
8    border-radius: 30px; /* or 50% */
9
10    background-color: black;
11    color: white;
12    text-align: center;
13    font-size: 2em;
14}