I hope I was explaining myself correctly in the beginning. Basically I am looking for the onMouseOUt for teh left and right divs to go back to its original width such as 50%. So the onMouseOver on either the left or right div will expand it to 80% while the right side decreasing to 20% This would work the same if for the other side too. When the user mouses over the right side which is currently at 20% the right div would expand to 800% and the left div will be at 20%. This transition happens simultaneously and is smooth. I was told the CSS3 property of transition would do something like this. AND I am only coding for IE 9+, Safari, Chrome, Firefox.