When validating the following CSS3 block:

  .style {
    --focus-indicator-color: #999999;
  }
  
  .style:focus {
    outline: 1px dotted var(--focus-indicator-color);
  }

The online service returns the message:

CSS: “outline”: “var(--focus-indicator-color)” is not a valid color 3 or 6 hexadecimals numbers.

Is this correct? The style is working properly on Firefox. I also tried with outline-color and it also fails. It seems that the outline color is not well defined, as it works when replacing outline with border.

Thanks for your awesome work! ❤️