How do I limit zoom out in Shortlist / change underlying background color?

[MarissaAltmann]

Hello! I am the owner of this StoryMap: http://wildlifefriendly.org/buy-wild/

I really hate the white box that surrounds the map, and the fact that users can zoom way far out.

We don't have any points in Antarctica / Greenland. I just can't get this to look nice. I'd like to limit how far out users can zoom, and code the white background to match the dark grey.

I have some experience in HTML, css, and js but clearly enough to help me here! 

One other option would be to change the trigger in js so there are only 2 columns at full view instead of 3. 

Really any suggestions and help in making this look a bit better would be great. We're a small non-profit so no funding for this type of thing unfortunately!

Thank you,

Marissa