Standard Disclaimer: This code is not official IDX Broker code. It does apply to thier pages, but in NO WAY is it supported by IDX Broker. DO NOT contact IDX Broker for any support of this code.
As seen in the IDX Broker DevSummit Presentation. http://www.slideshare.net/IDXBroker/advanced-customization-alec-and-antonio
IDX Broker can have different CSS rules based on whether or not the visitor is logged in.
This can help you to easily change content for the public versus leads that have already signed up.
As always, be sure that any changes don't violate MLS rules.