Mobile menu background changed to "nav active" color

Site URL: https://heartpainter.com/

I changed some site design colors today, and didn't notice for quite a while that if the mobile menu background color is now the same as the "nav active" color, with white text. It used to be white with black text, which I'd prefer. Or at least, I'd like to be able to adjust the menu background by itself. This seems weird to me. I'm using Wells template, if that matters.

I found some custom css here that I put into Custom CSS as below, changing background to white. This recreated the problem of clicking on a mobile menu, then full size view, wrecking the design completely. So...any ideas as to why? I took the code out and the problem disappeared, but there must be a way to get back to a plain white menu in mobile views, with black text. Much easier to read and less distracting.

Add to Home > Design > Custom CSS

@media screen and (max-width:768px) {
div#overlayNav {
    background: red;
}
}

Have you solved it yet?

I just left the mobile menu background the "nav active" color and everything works. Maybe it's my imagination that the menu background used to be black text on white. I've been working to revise the site over the last three weeks or so, but it had been a couple of years since I changed anything or scrutinized how everything looked.