"Make the Add to Cart button blue" is fine as a first step. When that doesn't have the desired result, I would simply revert the change, start a new session, and do something like "Give the Add to Cart button its own theme separate from the default button theme. Make the color for this new theme blue.". If this gives almost the correct result (e.g. it's not the shade of blue I want) I'd do a followup like "change the Add to Cart theme from #00FF00 to #16b8c4" with no implication that the previous step was wrong. If it's wildly incorrect I'd start over and try to specify in more detail about what exactly should happen.

If I don't understand why changing one button changed them all, I would use an entirely separate session to ask questions about how the site theming works. The fact that the site has a bunch of weird coupling between themes is useful information, and if I don't know how to resolve that I'd ask Claude for ideas about how to safely eliminate the coupling, and once it proposes a reasonable idea tell it to implement that.

The two big things here I'd never do is use emotional languages in prompts, and I'd never tell Claude to revert changes and try again. Once the incorrect change is in the context it's poisoning all of your future results.