Worked as expected. You do have to adjust the broswer size to see it popup and be active. Then adjust the hide delay size for a little longer to see it for a bit when making adjustments. Was looking for a small plugin like this and it makes it super fast and easy to find.

Thanks! It works.

Just this is the addon I want/need as a web developer especially in the field of responsive web design. Thanks the developer.

This is exactly what I want, so thanks. One note - it did not work for the first few minutes, so if you are trying this out, a little patience.. don't know what I did to get it to worl.

Really, really useful tool for developing the way a web page behaves with responsive CSS and javascript kicking in at different screen widths. I've been wanting this functionality for a long time, so brilliant to have such an easy-to-use and neatly implemented tool available. Many thanks and kudos Luke Peters.

it's a pretty good extension, but when I set for body element text-shadow is used also for extension span element.

Thank you for this! I've been using it for a while and it's a vital part of my workflow :) One tiny quibble if I had to: it does pop up when entering full screen mode on a YouTube video for instance, but that might be unavoidable and it's hardly a big deal

Excactly what I needed. Only three suggestions:
1) don't be shy with the z-index. I installed and I thought it wasn't working until I realized there was a fixed header with z-index 99999 on the site I was testintg.
2) a few size options. I wouldn't mind a tiny one to use always on.
3) use pointer-events: none so we can click through it :)

Safe and does exactly what it says.

A suggestion would be to make an option to make the box stay and not disappear after 1-10 seconds.

Works perfectly for the sites I'm working on. It didn't work for this page of the review due to:

Content Security Policy: The page’s settings blocked the loading of a resource at inline (“style-src”).

But perhaps there's nothing that can be done about it?

Thanks for writing this very much needed extension

Works perfectly, very simple and usefull for web developpers.
Thanx for this extension !

Works perfectly. love that you can change location of values.

Extension did exactly what I wanted but I've had to uninstall it due to it causing the following error in my console:

Error: Permission denied to access property "apply"

No option to change the position of the little popup with the viewport size...