The `Download as HTML` button doesn't keep CSS styles

So what I found interesting, is that the method described here:
https://github.com/KeithLRobertson/markdown-viewer/issues/35#issuecomment-389544845
Works perfectly, however the `Download as HTML` button does not keep CSS and seems to have some weird formatting, here is an example file:

1. Original Markdown file: [schema.md](https://github.com/KeithLRobertson/markdown-viewer/files/8884571/schema.md)
2. How it's rendered in my browser: https://i.nuuls.com/BPDZX.png
3. File output of `Download as HTML` button: https://hateful-brick.surge.sh/
4. How the output is rendered in my browser: https://i.nuuls.com/SMbZy.png
5. Using the method described in https://github.com/KeithLRobertson/markdown-viewer/issues/35#issuecomment-389544845 file output: https://nine-club.surge.sh/
6. How it's rendered in my browser: https://i.nuuls.com/fOdkT.png

Start with the Download as HTML button and compare its output with the rendering method described in issue 35's linked comment. Use schema.md and the provided browser screenshots and hosted outputs to reproduce the formatting and CSS differences; done means the downloaded HTML preserves the expected styles and formatting.

Written by the indexing model from the issue text.