Colored Box Menu Items

Please help with CSS

1. There’s two colored boxes in the header. Let’s say I want to apply a different style to one of them. Whats the selector for the .not or .men classes I applied to these menu items. Or maybe first or last child?

2. Also, whats the best way to add a padding/margin between them?
I have this for now. Without it, they’re too close together.
#menu-item-3787 {
margin-right: 20px;
}