I went back to the merchant onboarding component and added a dark theme, but I didn’t want to just start throwing dark: classes everywhere. So I moved the colors, type, shadows, states, etc. into semantic design tokens, kept the light theme looking exactly the same, and added a simple Light / Dark switcher that follows your system theme on first load.

The theme switch itself was actually the easy part. Most of the time went into making sure there was no weird flash on load, the transition didn’t mess with the existing Motion animations, and things like reduced motion, focus states, contrast, and the dropdown still worked properly.