I am having issues styling the menu. In Upfront, it looks

I am having issues styling the menu. In Upfront, it looks as if the menu background is transparent, and I have edited the main-nav code so that the background should not ever have a solid color behind it. When I look at the site live online, however, the menu background is green. I also cannot seem to edit the hover function to underline, it just underlines all the menu items. I don't understand how to edit these styles if I'm not able to edit the code. Please advise!