Changing mobile menu dropdown background color

I am having trouble changing the background color of the dropdown menu on the mobile version of my site. I was able to change it for the desktop version and for the submenu (under “Films”) on the both the desktop and mobile versions using the code:

ul.sf-dropdown-menu {
    margin-top: -44px;
    margin-left: 10px;
    background-color: #000000;
}

I want the background to be black, but the mobile menu has a gray color instead. I tried some different code but nothing worked.

The page I need help with: [log in to see the link]