Define background color for individual parent nice menu items with CSS

I am running Drupal 6 with Nice Menus and customizing a Zen theme. As such, I would really like to define different background colors for each of the menu items across the screen, with a uniform color for the drop-down menu below the menu.

I am having a hard time coming up with the proper syntax for the CSS code to be able to accomplish this.

In my custom CSS file (as defined in under themes>global settings), there is this:

ul.nice-menu-down li.menuparent,
/* Repeat for Garland header. */
#header-region ul.nice-menu-down li.menuparent {
  background: #eee url(arrow-down.png) right center no-repeat;
}

But I cannot get the syntax right to name each .menuparent by its ID number.

Anybody have more knowledge than me on CSS?

Thanks!