Having an animated image down the side of ForumHome

[Cloverfield]

I have an animated image that I want down the side of my index page. My index page is roughly 3000 pixels in length. What I want to know is if it's possible to maybe put a table or something in this side so that when the image is inserted into it it will adjust to the length all the time. Basically, the image is moving down the page and then empties into a drain at the bottom. You will be a god to me if you know how this can be achieved because obviously the image would easily get f**ked up if someone was to make a section despand or something like that.

Basically, I need it so that if someone collapses a section on the index page, the image kinda moves up with it, otherwise it's all gonna get really screwed up if it cannot adjust to what's happening.

If someone can point me to a modification that will allow this image down the side and for it to adjust when section are collapsed or expanded you will be a god!!