Style the pop up in WAB to match the configurable templates

[TracySchloss]

I often use WAB to take advantage of the widgets, and have always thought the popup styling seemed really out of date, compared to the rest of the application.  It defaults to black background with rather pixelated text that when expanded takes up the whole screen, whether there is 2 attributes or 10. 

Why not change this styling to match the pop ups in the configurable templates?  That popup default style is so much more attractive.  Then instead blotting out your whole map when you needed to see all the attributes, it would appear nicely below it.  I'm sure I could set up custom styling, but obviously somebody must have noticed this already at Esri, or they wouldn't have changed it for the newer templates.