Hi Volker,
Solutions for syntax highlighting were proposed by sstk and Kazar in
this thread:
http://groups.google.com/group/reposstyle/browse_thread/thread/11bf0f9d50a3111a
Repos Style currently does not display diffs, but it is easy to copy
the log php and modify it to run svn diff. The GeSHi highlighting
engine that Kazar suggests (see thread above) supports diff format.
/Staffan