This is my favorite theme, but some websites eliminate it and it is hell to ever get it back on. When I search for it, it only gives me the option to REMOVE it, not apply it.
I've had this add -on since it came out 8 years ago. Totally reminds me of my den in the old house. When one of the updates said it wasn't compatible with that version of Firefox I was sad, but then the next up it worked just fine and has be fine ever since. So off to the walnut paneled browser.
