Seeking regex remap:exclude .css files proxy

System

I need a regex that excludes css files in workarea from going thru the proxy.

When I use
pattern to match:
iw-mount/default/main/tim/Release_00/WORKAREA/Pim/(.*\.[cC][sS][sS]$)

replace with
http://devkennism-01:87/tim/System/TeamSitePreviewer.aspx?FileLocation=/$1

sample input
iw-mount/default/main/tim/Release_00/WORKAREA/Pim//global/includes/stylesheets/content.css

Match, input changed to:
http://devkennism-01:87/tim/System/TeamSitePreviewer.aspx?FileLocation=//global/includes/stylesheets/content.css

But I cannot find the correct regex for excluding .css files.

Any help welcome
Marcel Somers