scrollbar-color: yellow blue !important;
  }
.... doesn't change anything.  Is there some complete guide to controlling the srollbars?  Nice if it could all be handled in one place of course.

A while ago I made some changes in about:config and also in my ~/.config/gtk-3.0/gtk,css file so as to control my scrollbar and slider -- making them more visible: /* Log out, and back in for these changed to take effect: */ scrollbar { background-color: #cccccc; } scrollbar slider { min-width: 20px; } /* dark green: pointer is not in the active window */ scrollbar slider:backdrop { background-color: #00aa00; } /* green: pointer is in the active window but not on a slider */ scrollbar slider { background-color: #00ff00; } /* dark red: pointer is hovering over slider but mouse button not pressed */ scrollbar slider:hover { background-color: #aa0000; } /* red: slider is active */ scrollbar slider:hover:active { background-color: #ff0000; } /* No effect: */ /* scrollbar-color: blue white; */ ----------------------------------------- ... it works half the time. Some pages obey the above settings but other pages continued to show a scrollbar about a mm wide with the slider so faint as to barely be visible. So, in 'about:config' : widget.non-native-theme.scrollbar.size.override 30 ... at least made the narrow scrollbar a bit wider. But how to change it's color? Doing this in a file: ~/.mozilla/firefox/5dqk4533.default/chrome/userContent.css: html,body{ scrollbar-color: yellow blue !important; } .... doesn't change anything. Is there some complete guide to controlling the srollbars? Nice if it could all be handled in one place of course.