Number style filter working.
Now want to fix up the styling a little and it will be ready for next push.
Have put in a switch so that I can apply the changes to all pages, or just the one.
Finally, I need to put an option to persist the changes or not. So like whenever a tab is opened, those fonts will show.
This can be a checkbox.
To persist the changes, every time a tab is opened, it will need to apply the styles. So it is pretty straightforward. The function to apply the styles already exists on the contents page. I just need to save the font family, weight, and style somewhere (background page) and then apply them whenever a new page opens.
So I will have an object in the background page. Each object within it will be identified by a selector.