I want to use this functionality in my web site (when press in 'SHOW IT') --> http://labs.voronianski.com/jquery.avgrund.js/

The problem is that this functionality need to put body height to 100%. In some time, in me site I need to detect the scroll user to make top bar appear and disappear em some positions.

So to can join this two functionality's, I only change body height to 100% when I press button to show the div avground. But where I have a problem: the button is on page footer and when I change body height, they automatically send me to the top of page and after show the div avground.

Is any way to this don't happen or is possible to scroll to footer before the div avground appear?

If someone have another solution, I appreciate.