Var for scrollbar size

Hey Dub Stylers!

Not sure why I never thought of this all the times I have needed it, but
after running into it again today I started wondering why there isn't a var
in CSS that represents scrollbar size?

I would love to have a var like currentColor that stands for the scrollbar
size; it would really help in layouts where you want to prevent snap from
scrollbar appearance, accounting for fixed element overlap of non-viewport
scrollable elements, etc.

So how 'bout it, anyone up for scrollbarSize? :)

Let me know what you think,

- Daniel