Side menu bar colour change?

Can the side bar colour be changed to anything other than black? For some reason I can only get mine to change text colour, or a section of the menu if I use code in classes. But not all of it.

So for instance: if a site background is white, the side menu will always open in the colour black with text colour of my choice. I am finding it rather strange to see why it is not changing the whole side menu to the colour I would wish?

Are you talking about the special (drop down, sidebar) menu?
Not sure but you might want to check out this video:

Thanks Teefers…I will check that now and let you know if it is correct or not for what I need.

Thanks for the help.