It there a way to get current margin for the element and increase it by value?

[greenjack-z]

If I add some element which properties assigned by third party css stylesheet and I want to increase it's actual set margin by 1.rem?
something like margin += 1.rem

[bitspittle]

I believe you use calc for that
https://developer.mozilla.org/en-US/docs/Web/CSS/calc