top-menu and/or sublist change background color not working

trying to change the background color of the top-menu which holds the category names. I have tried changing top-menu and sublist items background colors although nothing seems to work. Anyone know how to change the background color of where the categories are displayed?

I'm assuming that you're using DefaultClean theme.

For TopMenu:
Presentation > Nop.Web > Themes > DefaultClean > Content > css > style.css

Find class css .header-menu

.header-menu {
  position: relative;
  z-index: 5;
  width: 980px;
  margin: 0 auto 30px;
  border-top: 1px solid #ddd;
  border-bottom: 1px solid #ddd;
  padding: 25px 0;
  text-align: center;
 } 

Add there background-color property:

.header-menu {
  ...
        ...
        background-color:antiquewhite;
} 

For sublist, find css class .header-menu .sublist and add background-colorproperty:

.header-menu .sublist {
  ...
        ...
        background-color:aquamarine;
}

Side: To making changes in default clean them wouldn't best practices, create your own css and override css classes from it. Here I've given quick example

that's great. thanks.

how can I make the menu wide to fit the whole page,

thanks