CSS variable declaration throws error in customizer

Hi,

I was trying to declare some custom color variables with :root, like this from an example from Mozilla’s documentation:

:root {
  --main-color: hotpink;
  --pane-padding: 5px 42px;
}

Put said code in “Additional CSS” in the customizer, but it warns me and tells me that it

expected RBRACE

in every line with a variable/starting with --.
Usually the customizer’s warnings are correct and I forgot a curly bracket or a colon somewhere, but this time I guess it’s something else.

Is this a known bug? Is there a workaround or do I have to save my edits to my child theme’s style.css (which I’d like to avoid).
I tried to google the problem but I didn’t find anything.

• This topic was modified 4 years, 6 months ago by nopewhy.