Secondary-Nav drop down color

Hi

I’m having no success in changing the color of the links within the secondary navigation drop down menu. I’ve created a custom link (with no actual link) to form 3 sub menus.

I cant work out how to change the background color of the drop down menu elements to white instead of grey.

I’ve tried the following code;

@media screen and (min-width: 769px) {
.secondary-navigation .menu ul a {
background: #ffffff !important;}
}

I’m using the Theme Customization Plugin to make my changes.

Any help appreciated!

Many thanks
Aaron.