How to get rid of the grey rectangles in widgets?

Can someone tell me how to get rid of the little grey boxes that are standard in the Atahulapa widgets such as Tags, Categories and Archives? I can't figure out how to style them and remove them all together. I don't want any bullets or anything. Instead I'd like to be able to change the hover colour when someone puts their mouse over the month, category, etc.

see here: http://www.unbecomingmymother.com/

I'm very new to wordpress and the atahulapa theme, so if someone could be as clear as possible when explaining, I would be very very grateful!

Thanks in advance!