I got a problem trying to change background color to transparent or something else but when I was trying to do that, the area I needed to do that goes Blue. This occured only with Firefox but no IE. So, I searched for information and found that it's something in the BODY. Since I used mainly TABLE, I have to put
style="background:transparent"
together with TABLE tag. By trying to put it in TD, or leave it out didn't solve the problem.