Responsive Child Theme Header Menu Background Color

Sorry if I’ve posted this in the wrong place. I have searched for previous responses and tried many of the recommendations posted, but I cannot get the background color of the header menu in Responsive Child theme to change color. In my custom CSS, I have the following:

site: https://www.pricedrighttablets.com/wordpress

.menu {
background-color: #FFFFF;
clear: both;
margin: 0 auto;
border: 1px solid red;
}

It works when I make the change in Firebug, but I cannot seem to change the color in CSS. Any suggestions greatly appreciated.