How do I get rid of an element’s offset using CSS?

That offset is basically the x,y position that the browser has calculated for the element based on it’s position css attribute. So if you put a <br> before it or any other element, it would change the offset. For example, you could set it to 0 by:

#inputBox{position:absolute;top:0px;left:0px;}

or

#inputBox{position:relative;top:-12px;left:-2px;}

Therefore, whatever positioning issue you have, is not necessarily an issue with offset, though you could always fix it by playing with the top,left,right and bottom attributes.

Is your problem browser incompatibility?