styling dropdowns and checkboxes

Hello, I would like to change the style on the form drop-down menus and check boxes to be larger. I was able to change the text fields only. Where would I do this? or maybe it’s a conflict with my theme stylesheet. Also, I tried to bring up the fields to one line and wasn’t able to…for example, Event starts at: with everything on one line instead of stacked:

http://durhamregionactionnetwork.com/submit-an-event/

Thanks for any help you can provide!

http://ww.wp.xz.cn/extend/plugins/events-manager/