Header Navigation - too transparent

Site URL: https://www.thiscitymaps.com/

How do I change the background of the text so that it is opaque instead of transparent. When I click the dropdown for the menu on the side it shows up like this and is hard to read. 

Note : this only occurs in mobile or when you have the browser window small enough that the pages do not have room to display at the top of the page. I am using the Hester template in 7.1

It seems you solved with this CSS?

.header--menu-open .header-menu .header-menu-bg {
    background-color: #fff;
}