$(\".block li\").hover(
function(){
$(this).animate({backgroundColor: \"#000\"});
},
function(){
$(this).animate({backgroundColor: \"#fff
Edit: I have tested this and it works.
Create two classes. One with background: #000 and one with background: transparent;
Animate the toggleClass or removeClass for the #000 background class.
example:
jQuery('.block li').hover(function() {
$(this).toggleClass('blackClass', 'fast' );
}
CSS:
.blackClass { background: #000; }