Issue with Expressions theme

Hello, I am having a problem with Event Registration and the Expressions theme. When I activate the ER plugin, I have the following problems: extra whitespace on the home page; highlighting of the menu items doesn’t go away when I move from a menu item; and non-homepage pages do not resize for content (longer pages have their content cut off). I found another person who said that wrapping the {EVRREGIS} in <code> fixed a similar menu problem, and that did fix the menu problem for me. Does anybody have any suggestions for the other problems with the page sizing? I also asked the theme developer about this. The web site I am doing is for a non-profit singing festival in my area: PghYouthHarmony.org. Any help greatly appreciated.

https://www.ads-software.com/plugins/event-registration/