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)