Format of downloadable versions of BioJupies notebooks is problematic

[KMJ1618]

BioJupies successfully generates notebooks using GEO data. However, once the notebook has been generated, there is an issue with the formatting of the notebook when the user left-clicks the Download icon in the upper right of the notebook display; I'm attaching an example screenshot to show the appearance. The URL of the corresponding generated notebook is https://amp.pharm.mssm.edu/biojupies/notebook/SHVzwlQLk

Right-clicking on the Download icon does successfully allow the generated notebook to be saved in .ipynb format.

Erol advised that this issue might be more broad than just BioJupies, and could involve NBViewer:

Unable to download form [sic] nbviewer #756
jupyter/nbviewer#756

According to Erol, the readable MIME type might be the problem.