A material chrome-like theme. Remember the material design in the new edition of Chrome? Well then, they have already arrived here in Pale Moon.
A fork of PMChrome, which is a fork of the theme FXChrome by dkgo.
Simply download the contents of the "src" folder and pack the contents into a .zip file. Then, rename the file to .xpi and drag into the browser.
Check the releases page of this repository or visit its page on the Pale Moon Add-ons Site.