Some misc clean up in the css.
The `background-position` is wrong here. Those two settings are here almost from the beginning and we've rewrite the card template few time since. By forcing the `top` position, we prevent the image to be centered. The `#cards td label` is very old also and was used to make the label in the card `clickable`. Now that the whole card is a link, this is no more necessary (and already unused).