how to change the navigation's background color?

JH

hi,all.I got a problem that i can't change the navigation's background with the basic css style.

my css:

.myNavigationStyle
{
backgroundColor: #FF0000;
}

RobertScheitlin__GISP

J H,

   

esri|Navigation
{
    background-alpha: 0.8;
    content-background-color: #ff0000;
}