The validator is having a problem with custom properties.

[adrianoenache]

Hello there

The validator is having a problem with custom properties.

To reproduce use the link below.
https://adrianoenache.dev.br/fcc-projects/responsive-web-design/tribute-page.html

I open an issue related to custom properties inside RGB and RGBA functions, in the markup validator, the same problem is happening here. Take a look at the link below.
w3c/markup-validator#61

Despite the error, it is working in the browsers I tested on mobile and desktop on Edge, Chrome, and Firefox. So I think this is a bug in the validator.

[ylafon]

fixed by #316 (now remains implementation of css-scrollbars)

[ylafon]

and scrollbar-related properties fixed by #318