"stylesheets"...

You should only have one stylesheet, not three main stylesheets. It looks like you tried to upgrade without going through the proper procedure, leaving both of your original 1.3.0 stylesheets in place - or did you even upgrade at all? Your site is still table-based.

The styling of your site is so simple that it could be replicated in an hour on a clean install. I don't think it is worthwhile to continue fighting with the frankenstein stylesheets you have going here. Save them somewhere offsite and copy relevant properties bit by bit into a new v1.3.7 stylesheet, on an upgraded installation. You can import your database so you don't lose any information. See the FAQ/tutorials for upgrading info.