CSS Design System - How do you handle anomalies?

I'm thinking of making a CSS design system which includes classes like

.text-red {color: red}

However, I have one question I can't solve, how do you handle anomalies (one of events). A common example could be making an element darker for say one element but the rest aren't affected in anyway.

Im super confused, I love the design system approach but anomalies are a big concern.