Either IE is dumb, or I am

[maxxd]

Hey y'all.

 

I've got the following code:

$(window).scroll(function(){
	if($(window).width() > 640){
		$('#bg').css({top:$(this).scrollTop()});
	}
	if($(window).width() > 981){
		$('.switch').css({top:$(this).scrollTop() + 75});//75 pixels is the top-offset of the element in the style sheet
	}
});

In Firefox, Chrome, Safari, Opera, and Chrome Canary on osX and Firefox, Chrome, and Opera on Windows the div 'bg' stays pinned to the top of the browser window when I scroll. Exactly as intended. Unfortunately, in IE, the div scrolls downwards (against the mouse scroll). But, the 'switch' div stays put - just like it should! It's acting as if the scrollTop() call is returning negative numbers, despite the fact that it's not (I've logged to console and everything looks fine) and it's only doing it in the first conditional. If I change $(this).scrollTop() to a flat 0, it works in IE but nowhere else.

 

I'm starting to doubt my own sanity. Can anyone come up with a reason I might be seeing this behavior?