Liquorice image click issue

I use liquorice 1.5.7 at thewinechixs.com and have modified some php along with CSS for my needs. I don’t do anything too radical, just use png images and put in a header image. The header image is the problem — when it is clicked on for Home the image has a white border. Nothing in CSS is white and on-click. Photoshop had a white border on the background layer but this was flattened. Can someone with better skills than I see immediately why this is happening, please?