New Browser Fallbacks in CSS Section

Going back through CSS curriculum I found this new exercise that makes no sense to me in it’s context.

I cannot recall reading anything about :root or var in The CSS section. Can anyone advise me where to find this info?

the answer seems to be in the following exercises. Makes me wonder if these are updates or I simply forgot them.

It depends on when the last time you did this section was. A lot of content was added in the last year.

I completed the content about a year ago and recently came back to find there were a few new lessons added yes.

There has been a TON added in the last year. Feel free to skip any topics that you already feel you know well. There’s no need to go back if you don’t want to.