New error appearing on CSS validation
I am getting this error:
Errors: 1 Instances: 1
Org.w3c.css.properties.css21.Css21Style cannot be cast to org.w3c.css.properties.css3.Css3Style - Instances: 1
style.css - Instances: 1
It even shows on previously validated style-sheets - it has no reference to any particular line in the CSS either.
What does it refer to?