Web App in Airplane mode/offline state?

Hi, first off, **love** the app, this is amazing as a non-webdev™️ that I can get a web app up and running in a couple minutes!

Second, I'm having trouble getting (my hacked up version of) the Savings Calculator working on my android phone. I'd like it to work when I no service (think airplane mode) and the style sheets and plotly are linked from other sites. What I did to solve this is:

- Grab the assets (plotly and both css files) and add them to the project manually (i.e., file>create, copy+paste).
- I modified the references in the index.html file to point to just their filename.
- I then downloaded a zip with everything in it to my phone, unzipped, and tried to run the app via opening the index.html file directly in chrome.
- When I did that, it wasn't able to access the local plotly or css files.

I can provide the relevant app/snippets if you need them to debug.