Checking the error logs I see a bunch of 404s for this file:
wp-content/plugins/gravityforms/css/images/ui-bg_flat_75_ffffff_40x100.png
It's being called from http://www.example.com/wp-content/plugins/gravityforms/css/jquery-ui-1.7.2.custom.css line 53. I can't tell that it's missing, I am just seeing the 404 being logged.