A: 

Probably can't remove filter from the <div> because it has no filter property.

<body> is the tag with the property; after some messing around

document.body.style.filter = '';

Removes the filter (but obviously, from the whole body).

Andrew67
Thanks for looking at the problem. I thought the filter property would be inherited by the div — no, wait that doesn't make sense... I can't seem to get the desired result with element.style.filter = '';
Louis