Downloading all images is out of the question. You use the most commonly used image as default and when the stylesheet is done you download whatever img is need

Downloading all images is out of the question. You use the most commonly used image as default and when the stylesheet is done you download whatever img is needed. Or, you use the newly minted 'defer' (I just came up with that) attribute to let the browser know not to download anything until the stylesheet is parsed. <img src='myhugeretinapic.png' defer>