How to change the background color of drop down menu in nav debut theme

when I click on the Shop All link in the nav bar there is a drop down that appears. Its a rectangle with a white background. and the sub links are “visible” but the font is white and does not show up on a white background until you hover over the links. I want the background to be black and the font color white all the time. I dont care if there is a hover effect on the sub links.

I have played with the below code but cant seem to get the results I am looking for.

.site-nav .site-nav–has-dropdown .site-nav__link–button {
color: #ffffff !important;
}

/.site-nav__dropdown li a{color: #000000;}
/
.site-nav__dropdown li a:hover{color: black;}

Hi

Check this below code

.meganav {
display: block;
visibility: hidden;
right: 0;
background-color: #ffffff; to #030303;
}

.meganav__link {display: block;
color: #fff;
padding:5px 10px;
margin-left:-10px;
}
.meganav__link:hover, .meganav__link:focus {
 color: #fff;
}

Thanks.

this did not fix my problem. I still have the same issue

Can anyone else give input to my problem? Still looking for an answer.