I\'m trying to do something like this for a client who has a blog.

You can also use border-style: double with background-clip: padding-box, without the use of any extra (pseudo-)elements. It's probably the most compact solution, but not as flexible as the others.
For example:
Some text goes here...
.circle{
width: 100px;
height: 100px;
padding: 50px;
border-radius: 200px;
border: double 15px rgba(255,255,255,0.7);
background: rgba(255,255,255,0.7);
background-clip: padding-box;
}

If you look closely you can see that the edge between the border and the background is not perfect. This seems to be an issue in current browsers. But it's not that noticeable when the border is small.