I came across a tutorial on custom borders with advanced CSS which explains how to add nice curved borders around HTML elements and such. The example that the author, Roger Johansson, uses, is very pretty, so I turned it into a template for Tellico.
Download Berean_Curves.tgz, and unpack it in your
directory. You may have to create the tellico/ and entry-templates/ directories. Then select Berean Curves in the template configuration. Voila!
It uses some CSS3 techniques, which only work in KDE 3.5, I think. Or at least, work less well in KDE 3.4 and earlier.