Indexhibit Support

I'm trying to change the width of my paragraphs so that you don't have to scroll to read, as on this page:
blairsubbaraman.com/index.php/project/geometry-synthesizer/
I've tried to edit the width set by #exhibit p in the style.css file, but it doesn't seem to do anything.
any help is very appreciated!

Im also having this problem - I'd like to vary the paragraph width in the visual index style
fearghusraftery.com/index.php/architecture/the-department-of-atomic-health/