I think the game has been updated, now the opacity of both colors are the same (255) but you can sum R, G and B parts. The highest will be the brightest.
function c(i,j){return $("#color-"+i)[0].getContext('2d').getImageData(0,0,1,1).data[j]}
setInterval(function(){$("#color-"+(1+(c(1,0)+c(1,1)+c(1,2)<c(2,0)+c(2,1)+c(2,2)))).click()},1)
Google Chrome on Win 7, 64 bit - all pages report "not found". Also behind a companies squid proxy if that might have something to do with it.
Make it work please! It's cool idea, good for showing some design changes without having to change anything in the original page, not even a detection if someone wants to see the new preview etc.
(You need to expose the pixelCanvas globally first using a break point or something)