1#avatar {
2 /* This image is 687 wide by 1024 tall, similar to your aspect ratio */
3 background-image: url('http://i.stack.imgur.com/Dj7eP.jpg');
4
5 /* make a square container */
6 width: 150px;
7 height: 150px;
8
9 /* fill the container, preserving aspect ratio, and cropping to fit */
10 background-size: cover;
11
12 /* center the image vertically and horizontally */
13 background-position: top center;
14
15 /* round the edges to a circle with border radius 1/2 container size */
16 border-radius: 50%;
17}