Question

I’ve seen it done, but can’t really find how to do it… I’d like to have one background in an alert message on page load and then, after couple of seconds, slowly fade it into white. Just the background — the message stays.

Answer 1

You will want to look at the color plugin or reference jQuery UI to do the color animations.

Quick example:

body{
    background-color:red;
}

$("body").animate({
    backgroundColor : "white"
}, 5000);

jsfiddle