By default, images align their bottom edgeswith the baseline of the text. That gray space you're seeing is thespace below the baseline, used by decenders like q, p, y, etc. (Thefact that you have no text is irrelevant - space for descenders isstill reserved.)
You can get rid of it like this:
a img { /* You might want to make this rule more specific! */
vertical-align: bottom;
}
See That mysterious gap under images for a full discussion of this.


