I was looking at something a bit curious – I wanted to change the menus in SharePoint, specifically the colour down the left hand side of the menu:

As the menus are dynamic, I wasn’t able to interrogate them with the IE Dev toolbar to know what styles were being applied. I took a screenshot and tried looking for the colour of the bar in the CSS files. It wasn’t there.

Huh?

Well, I realised that I’d have to trawl through the CSS searching for a likely looking class. I tried Core.css and found the ms-MenuUI and ms-MenuUILarge classes (also defined in the in the Menu.css file, for some reason).

These use images for those bars! Ah! Changing them results in my new background image being used:

Sorted!