Hi, concepta.
On the demo website the top footer has a background colour that is set in the skin’s stylesheet, and the bottom footer is transparent. That’s the default. There is no option to make the top footer transparent, and the only way the bottom footer can become opaque is if you set a background colour in that footer’s static content.
If I have misunderstood your question please explain in more detail what it is you are trying to achieve. A link to a live web page that displays the issue might help me to understand.