great extension!

Excellent

this add on works perfectly in firefox v64
And i love the size of this add on
Thanks a lot Mr. Keith L Robertson

I had to follow the instructions on the home page to set up the markdown mime type on linux, and with that it works marvelously.

I use it to copy the webpage link into LaTeX with the hyperref package. I modify the default markup syntaxis with one appropriate for LaTeX (plus hyperref):

\href{${page.url}}{${page.title}}

Works perfectly on linux after adding mime type.
Don't forget to click on the toolbar icon to enable markdown rendering for local and web files

Exactly as advertised. I open .md or .markdown files in the browser and this "beautifies" them. Many thanks!

One suggestion I have is to have a "dark mode" that inverts the black on white or to have a "Custom CSS" box in the settings that would allow us to adjust this.

If this plugin is available on GitHub (haven't checked yet), I might consider making a pull request to implement the feature ^ mentioned above.

Edit: Fix typo

Works fine for file opened locally - raw markdown is displayed initially and upon clicking icon it is rendered correctly.

If firefox does not correctly assume that your files are UTF-8 encoded, a possible solution (besides using a Byte Order Marker in your file, which is annoying for several reasons) is the following:
go to about:config and set the intl.charset.fallback.utf8_for_file variable to true. That worked for me.

This is related to the following bug report:
https://bugzilla.mozilla.org/show_bug.cgi?id=1071816