Changing GTK Theme

How do I change my GTK theme?

On my Arch rig I use the Adapta theme and I used lxappearance to change it. I found both packages in nixpkgs but lxappearance is not working. Clicking “apply” in lx appearance has no effect.

I use Sway as my compositor so specific applications for particular display managers is of no help.

Thanks for your help,

The lxappearance package defaults to gtk2, you probably want