Changing a Navbar transparent default to white., Help to just change a small CSS element in a Wordpress theme Options

[mfdc]

Can you help me please?

If you look at the following site, (www.acumenprojectsltd.co.uk) you will see there's a transparent nav bar which turns to white on page-scroll. I want this nav bar to be permanently white, & the menu options to be black.

Now, I've used DOM explorer to highlight the CSS elements, confirmed there's specified in the style.css file, and attempted to modify the -transparent value to #fff; but this doesnt work.

Can someone help? CSS file attached