I was just using Safari and thought something seemed off with the color, and it turns out I was right! Safari exhibits banding in gradients and other color abnormalities where Firefox has no issues. I'd really appreciate it if anyone else with an rMBP (or other machine, if others are affected) could confirm the problem: Try visiting this test page in both Safari and Firefox and check if there is vertical banding in the gradients. Also, you could try checking the background of Ars Technica for horizontal banding. Lastly, look at this gamma calibration test with both Firefox and Safari and check if Safari is way off the correct values (for me, Firefox passes the test but Safari isn't even close).