jquery fadeins and fadeouts on CSS properties

In this fiddle ( http://jsfiddle.net/mjmitche/KvwGw/33/ ), when you click the send button, the form fades out, and a new form appears. At the same time, the CSS background color changes. The 开发者_运维问答code below does that

I am trying to put a fadeout and fadein on the CSS backgrounds (to coincide with the appearance and disappearance of the forms) but can't figure out how to combine fadeins and fadeouts with css elements/properties.

Any suggestions for a newbie would be greatly appreciated.

Note, on my live site, it's background images that are changing but it's happening very abruptly, so I want to put fadeins etc on them

I think the second answer in this discussion is what you're after. Hope that helps