Design for options page

[airtower-luna]

The options page right now is very much a "works for me" style. It'd be nice to have proper CSS styles, and maybe an updated structure too. Input validation before saving would be a plus.

AMO documentation recommends using the Photon Design System.

Some potential features like source match (#15) or regular expressions (#6) will need room for configuration, so opening a separate setting page instead of including options in the add-on view might be better to have more room.

I'd rather not add any dependencies.

[airtower-luna]

Another consideration: The table style doesn't scale well on small displays (like mobile devices). I wonder if there's a better way to do it, maybe with elements that arrange in a table-like grid if there's room, but collapse into individual boxes with their own labels if there isn't?

[Gitoffthelawn]

Maybe a flex grid?