问题
Just placing a DIV with white background and any opacity value:
background-color: rgba(255, 255, 255, .5);
over a white (255x3) background. Actually DIV's background will be 254/254/254. This happen only in Chrome. FF/IE/Opera/Safari is ok.
Bug?
回答1:
This looks like a bug!
I can confirm this misbehaviour. Got it also by using background: rgba(255,255,255,0.1). More weird: the calculated style says background-color: rgba(255, 255, 255, 0.0980392)
It is hard to see on cheaper displays using TN technology, but still possible to screenshot and measure with e.g. Photoshop.
This question is similar to:
webkit bug: input's background gets gray without any reason on focus?
回答2:
The weird behaviour is still present in Chrome 38 and Canary 40. The fix that worked for me was to add a transform: translateZ(0); to the div with the rgba background.
回答3:
This can now be fixed with the new will-change property. Specifically, will-change: transform;
来源：https://stackoverflow.com/questions/18972313/css-rgba-transparency-bug-in-chrome