How do I change the transparent dropdown menu to white?

Site URL: https://moose-hawk-zh87.squarespace.com

Dear all,

I'd like to change the transparency of the dropdown menu in mobile version to white? 

The text can't be read now because of the transparency, so it looks awfull. 

Thank you all very much!
 

Add to Home > Design > Custom CSS

/* mobile overlay color */
.header-menu-bg.theme-bg--primary {
    background-color: white !important;
}

Thanks! 
The only problem now, is that i can klik on anything. It's kind of frozen, when I put that in.