Chrome Issue about jQuery animate and fixed element

This line will cause unknown black block problem in Chrome only:

#header{height:110px; position:fixed; z-index:10; background:url(../images/grid_bg.png) repeat fixed #FFF; top:0px;}

Solution: Remove background style – fixed!

#header{height:110px; position:fixed; z-index:10; background:url(../images/grid_bg.png) repeat; top:0px;}