I know it should be a simple job but I have been right through the css and have not been able to change the background of the word list title block.
I've attached a screen shot of what I want to change so if someone can point me in the right direction I would be eternally grateful.
Inspect the element which style you want to change.
Right-click the element and in a drop-down menu select something like "Inspect DOM element" or "Inspect element with Firebug".
Many browsers can do that natively, I personally prefer to use Palemoon browser with Firebug Add-on (IMO it's a bit more convenient).