Paste two colours. See if they hold up on screen and in print.
Screen colour is additive — your monitor emits red, green, and blue light directly. Print is subtractive — ink absorbs certain wavelengths and reflects the rest. Opposite mechanisms on the surface, but the same underlying physics: both are just light, measured in the same units, governed by the same equations. The difference is only where the photons originate. Which is exactly why a colour pair that clears every accessibility standard on screen can become illegible the moment it hits paper.