White space at bottom of anchor tag

The image is display: inline so it is treated like a character and sits on the baseline. The gap is caused by the space provided for the descender (which you find on letters like j, g, y and p).

Adjust the vertical-align with CSS: img{vertical-align: bottom}

display:block is sufficient for this, if the element has no siblings.

I had the same issue and i fixed it by adding to the 'a' tag display: block; and font-size: 0px;