Good Dev tools

This is a very very important extension for web designers and developers, in my opinion. Absolutely great for pixel-perfect designs.

Great add on to test and implement grids. Really usefull!

Two things I miss:

1. The grids I create are not saved?
2 Option to add and define a left and right margin/gutter. Often a grid will have a margin on eather side. E.g. if the gutter is 30px it typical to have a 15px margin. It would be great to see this too. See what I mean here:
https://i.imgur.com/rGCOrCC.png

Je m'en sers surtout pour les repères. Combinés avec la règles native de Firefox, c'est juste PARFAIT. Merci ;)