Hi Firefox user 14520466, thank you for your comments. Most of the buttons inject changes that are not visible until you use Print Preview. You need to preview after each change. I would prefer if I could integrate the extension into the Preview page, but I don't think there is a way to do that.

Meanwhile, that MIT Technology Review page is tricky. This could be a case where you want to use Reader View (look for the icon in the address bar) or the equivalent "Simplify Page" checkbox on Firefox's Print Preview screen to isolate the article content.

If you wanted to print with more of the other stuff on the page:

I updated the extension with a new button at the top of the drop-down that is much more selective in the changes it makes (*LIGHT* button in version 1.2). In order to avoid the repeated top menu bar on each page, or having to remove that bar, it's best to scroll back to the top of the article before printing.

----

(One day later) In version 1.3, I switched to automatically displaying Print Preview after each change. Hopefully this will be more convenient for most people. You can revert the behavior if you know you need to use multiple options on a page and don't want to have to cancel Print Preview in between.