I've been searching a long time how to draw a diagonal line with just standard Web features (HTML, CSS, DIV, etc). Most of the time I end up at Scalable Vector Graph (SVG). However there has not been a wide spread support for this technology on the client side. Microsoft is betting it's money on it's 'own' standard Avalon.
The W3C has one little note, that diagonal layout might be done without SVG, but the follow up link to these details is broken.
Today to my pleasant surprise, I stumbled on the information that Mozila has native support for SVG! This is opening a big door to get .SVG files to the clients desktop. Here is a view of a rule network dependency graph. Probably of more interest is the automatic detected rule contradiction. This rule anomaly was detected by the Policy Verificator that supports rendering SVG files.
For those stuck with Internet Explorer: you can view .SVG files with the Adobe plugin.