Hi Shivanand, I am new to ColorfulTabs. I was a long time user of TabMixPlus until FF 57 caused that functionality to be lost, at least for now. I was looking for an add-on that would allow me to provide a different color to the selected tab, and perhaps different colors to tabs that have been selected and those that have still to be selected. That brought me to ColorfulTabs.
From what I've read here, the only functionality at this point with FF 57 is that the selected tab is lighter than the other tabs. I'm using the colorfun rainbow theme. If it helps, I'm running Windows 10 with the latest updates and the Intel HD Graphics 4400 display adapter.
By the way, perhaps I missed it, but I couldn't find a description in the ColorfulTabs documentation that told how to manually install this add-on for FF 57. Fortunately, I knew how to do this, but there may be many who only know to click the Install button, and think that is the manual installation procedure.
Thanks,
Tim