Need Help Adjusting size of mobile logo and header

I am working on a wordpress website and I have the nonprofit theme I purchased from theme forest.

I was able to successfully change the logo size and bar for desktop but mobile is transparent and small.

I am hoping for a white background and the logo to show at a reasonable size and not sure how to add or tweak the css for this.

You can see the png has a white background to help me see it for testing purposes. but a white banner would be better as the hamburger icon is hard to see as a transparent.

The page I need help with: [log in to see the link]