Shift-Ctrl-M in Firefox

[JerryMungo]

Noice.

It may be old to some and I'm sure Chrome has a similar feature, but I just discovered it...

 

[Batista]

Did not know that, thanks!

 

[animal531]

Ah, pretty cool. I'm not really a web developer, but always good to know a few tricks.

 

[dhedderwick]

Thanks for this, really, really useful!

 

[Johnatan56]

Chrome has as well, it's DPI scaling isn't messed up, I find it works better.

Do note to refresh the page for things that scale according to JS. Some JS, like select2, will ignore the smaller window size.

You can access both FF and Chrome responsive design mode via the mobile like icon in inspector, top right.