If you want a very minimalistic theme for a Nikola-based site, I just did a quick and dirty port of Scott Wallick's blog.txt theme
If there is anything nice here, he did it. If there is something wrong or broken, I did it instead.
I did it basically to see if it was possible to port wordpress themes to Nikola. And it is, but it involves reading php files and loosely reinterpreting them into Mako templates.
While the port is far from perfect, it's a reasonable starting point for someone who is really interested in it.
Here is how it looks:
And here is the download. To use it, just unzip it in your themes folder, set THEME to "blogtxt" in your dodo.py file, and rebuild the site.
At least the CSS files are easily adapted.
This theme is under a LGPL license (see included license.txt), enjoy!