It's fairly simple to do, too...
The HTML I used uses inline CSS to manage the layout.
<FONT STYLE="color: red; font-family: 'Tahoma', sans-serif; font-size: 42pt">Back</FONT>
<FONT STYLE="color: blue; font-family: 'Tahoma', sans-serif; font-size: 78pt">Front</FONT>
It helps to put a few lines of padding white space around the code to make sure you don't get nasty layout effects...
(Update 1: Probably best if you look at this in a comment view to see the full effect.)
(Update 2: The LJ autoformat system mangled the DIV style I was using. So I have used <lj-raw> tags to fix it. See the code sample for the latest changes...)