Created attachment 8924218 [details] Screen Shot 2017-11-01 at 18.29.26.png User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:56.0) Gecko/20100101 Firefox/56.0 Build ID: 20171024165158 Steps to reproduce: Surf to http://mertiso.blogspot.ch/2016/08/how-to-make-your-content-go-viral-my.html . Actual results: The scrollbar slider is not visible. Although technically there, i.e. if you guess right, it responds to mouse input as normal, it is just not visible. Expected results: The scrollbar slider should be visible.
Fixed in Firefox 57.