I have installed the latest linux mint (19.1 Cinnamon) on my laptop, and downloaded the latest anki (v2.1.6) directly from the website.
Previous versions of anki were distributed as .deb files, but lately they have been simple .tar.gz files that you're supposed to simply extract to a directory of your choice and run.
This is the first time, however, that anki has failed to pick up the local theme; instead it seems to be using some sort of (I'm guessing) qt default theme, which in Anki's case looks a bit weird.
I've tried installing packages from the repository that seemed like they might solve the problem (e.g. the qt-adwaita package), but this has not affected anki in any way for now.
Is there a way I can tell anki to use the system-wide theme?