Navigation background color change on hover fill to full width of dropdown menu

Hello, I currently have custom css to make my navigation background change color on hover, but the background color only goes part way on the width of the dropdown menu. I'm new to coding, so I'm not sure how to fix this on my own but I was wondering if anyone knew how to fix this. I couldn't find any posts describing how to do this based on my verbiage for a search, but that may be because I do not know the correct terms for things. 

For example, it currently looks like this (how the highlight section has no padding on the sides of the word "about" & ends within the margins of the dropdown menu on "employment",

but i would like it to look more like this and stretch the whole way across the dropdown:

Thanks in advance!!

What is site url? We can check easier

@tuanphan it is bouldersgym.com

that works, thanks so much!