TOPMENU - How to change the background color ?

I created a custom style to hot_sportal template. I want to change the background color of the topmenu but can not find that option.
How to change the background color of the topmenu. In all the style to template background color is white.

Menu is targeted in css by #nav. Definition is in template_css.css.

#nav{
...
}

#nav li{
...
}

#nav li a span{
...
}

#nav li ul{
...
}


#nav li ul li{
...
}