Atlascope Tours: Responsively set width of captions

[itspangler]

The full screen width of captions on tours can make them difficult to read. I'm conscious that such a change would open a big can of worms, because if captions are not full screen, then they would begin to take up too much space on the actual map.

To account for this, possibly we enforce a character limit on the captions so that they would never overflow too much into the space of the map. Short captions are better anyway!

Another idea is to relocate captions from the bottom of the screen to a sidebar, and in doing so, offset the controls (scope/slider) from true center of the map to the center of the map and its sidebar. My sense is that this is undesirable because it's a computationally intensive process.

Perhaps neither of these end up needing to be implemented, but I wanted to log this for discussion.