Let me go into more detail because after looking over your links it sounds way more complex than it really is.
I have a forum I am tyring to edit a style for.
It was pro silver the default style by phpbb.
there is some blue #CADCEB that I am trying to make go away. I want to be able to see all the way though it so that its 100% transparent.http://www.tarantuladatabase.com/assets/forum
If its really that complex don't worrie about trying to explain i'm also posting on the phpbb forum so maybe someone there that has done it before can give me some advice. Its my first time trying to edit this part of a style so I really don't know what i'm doing.