Out of the post-(US)election haze, a new theme - Pseudobrutal - has arrived at the themes.tiki.org marketplace. This theme is an implementation of Brutalist web design. (See http://brutalistwebsites.com/ for examples and https://news.ycombinator.com, https://codepen.io/brianhaferkamp/posts/feed/, etc. for discussion of this design genre.
The upshot is that Pseudobrutal is a pretty minimalist theme with a few non-Brutalist visual details.