addons.mozilla.org domain disallows this operation, so this add-on will not work properly when it's run on pages in the
What it does
This extension just includes:
- a content script, "borderify.js", that is injected into any pages under "mozilla.org/" or any of its subdomains
The content script draws a border around the document.body.
What it shows
- how to inject content scripts declaratively using manifest.json