Transition is glitching during initial positioning #20

When applying transitions to the top/left properties of poppables, it "jumps" during the initial positioning, since the poppable is positioned outside of the screen initially. This phenomenon can be seen in this example: https://webrix.amdocs.com/examples/GuidedTour

To fix it, perhaps we should use another hiding strategy (i.e. apply some CSS to change the visibility rather than push it outside of the screen).