If that's your goal, you probably shouldn't call the class bg-blue? It should be bg-blue-but-purple-on-mobile. But then it's definitely so specific it's the wrong way to select a style. If you want the page background to be blue but purple on mobile, write that in your CSS with a selector of "body" instead of ".bg-blue-but-purple-on-mobile"
alt Hacker News
If that's your goal, you probably shouldn't call the class bg-blue? It should be bg-blue-but-purple-on-mobile. But then it's definitely so specific it's the wrong way to select a style. If you want the page background to be blue but purple on mobile, write that in your CSS with a selector of "body" instead of ".bg-blue-but-purple-on-mobile"