Header Customization

I have done a lot of searching about this. I have also dug down to see if I can change the CSS myself. With all those hours, I simply thought I should just ask.

On my site http://www.johnullyatt.com I would like the main nav to be transparent, or even better slightly opaque. I would like to be able to customize the text in the first “presentation” of the nav – make it white, for example; and have the dark theme for the second slide.

I tried using colour customizer, but it reverted back to black (and therefore not visible). With the Light theme, the text that is backgrounded by white disappears.

I am trying not to be a pain in the ass, and more self reliant, but frankly this has me stumped, and I can’t find the answer myself.

Any help.

John