I choose you, Safari!
Firefox, go!Shelfworthy—as it stands now—is being developed by a very small team that is trying to push the boundaries of web design. Because of this, and the time it takes to support non-compliant browsers like Internet Explorer, we’ve decided to only support Safari 3.0+ and Firefox 2.0+ for now. This might change in the future, but I wouldn’t hold your breath…
If you have a browser that you think should be supported, e-mail me at chris -at- shelfworthy dot com.