Change Grid Filter Menu Background

I am trying to change the background of the grid column filter menus from transparent to just a solid background. These are the menus that you see when you click on the arrow in the column headers and you see the drop down menu. I would also like to know what the official name is for these menus? I am still new to web development so html and css are still foreign. I thought this gridfilters plugin might be able to help me but I am not sure how.

If anyone knows how to do this or could send me in the right direction that would be great.

PS: It doesn't seem like a transparent background is the default for extjs 5 from the examples I have seen. I do not think we are using the most current version of 5. Could it just be a version issue?

Thank you

Change Grid Filter Menu Background