how to get rid of firefox image border

[ABIGOR]

I've recently added an image to my website, where the image is wrapped in an anchor tag, like this: .The problem is, that this image has a border, but only in firefox; no border is showing in chrome. I want the border to go away. I have set in the css for both the a and img tags, the following:\[code\]text-decoration:none;border-style:none;border:none;outline:none;box-shadow: 0;-moz-box-shadow:0;background:none;color:white;\[/code\]The image is a small gray icon on a white background, and I have double checked it in gimp and there is definitely no border around the image. So, what have I missed? Where is it coming from? Why does it only appear in firefox? And how do I make it go away?Firefox version is 17.0.1