I couldn't figure out where does this 1px height difference in chrome 2 px height difference in firefox and ie9 is coming from ? Seems like div.entry is where it's coming from, but I couldn't fix it.
#middle {width:900px;}
#middle div.homepage img {width:900px;}
Change
#middle div.homepage img {width:900px;}
to
#middle div.homepage img {display: block; width:900px;}