Properties are highlighted as cssProp even when used as values

[jsit]

Take the following CSS:

div {
  background-color: blue;
  color: white;
  transition: 0.2s background-color, color ease-in-out;
}

In the second line, background-color is a CSS property being assigned a value. In the fourth line, background-color is part of the value of transition, yet both are assigned to the group cssBackgroundProp.

They're related, but different things, and as such it would be nice if they had different highlight groups assigned to them.