How to remove the border from the header image itself?

I created a header in photoshop which dissolves into a white background. Because it doesn't fill the entire header image area and is aligned right, in some browsers there is a square border around the left side of the image. In other browsers it looks the way I intended and the image dissolves into the white background of the image header area. How do I elliminiate that border around the image? A link to the site for reference.