Welcome to Mobileread.
Originally Posted by heddhunter
That said, your utility is awesome... I gave it a shot and it looks like it will be really handy. Nice one!
When possible please do not reopen year old obsolete threads. There is a reason you were presented with and Old Thread Warning
when you went to post to this thread.
This feature is essentially built into calibre via the right click menu. Select the book you wish to tweak in calibre's library view. Right click the book and choose Tweak Epub, explode the epub and open the css in your favorite editor, I use notepad++. Edit and save the css, rebuild epub.