Why does Polaris use rem for all properties?

[sircumferencee]

I am trying to understand why would you use rem for everything and not only font related properties. Like why use rem for box-shadow for example?

[kyledurand]

If this is meant to be a discussion can you add some context or propose alternatives? There are plenty of examples of why rem is better than px / em but opinions can go back and forth

[sircumferencee]

I am trying to understand why you would want your box shadow to scale with root font size