Image size on gigapixel storymaps

Hi There. Great tool, you guys made, but there's one thing I'm hoping you could help me with. When I make a gigapixel storymap, my title slide will only show the image kinda small like this example:

http://cdn.knightlab.com/libs/storymapjs/latest/embed/?url=https://www.googledrive.com/host/0B1d8oNIpMx53anVuVUFOTXlOVXc/published.json

I really want to have my start image shown bigger more like this example:

http://cdn.knightlab.com/libs/storymapjs/latest/embed/?url=https://www.googledrive.com/host/0B1d8oNIpMx53Wk9CdDlVZ01qU1E/published.json

But I can't really see an option to make this happen. It's making a small 'full viewable' amige as default it seems.

Is there any way around this?

Thanks again for great tool.

Best, Peter Jorgensen