[amelius]

Simple.

Red is a warning color, also has bad contrast on white background.

Green on white has bad contrast.

Blue has best contrast on both white and black backgrounds, and stands out from black.

Clear winner.

(Virtually everybody who ever made a PowerPoint presentation figured this out)

[smj-edison]

Side note: agree with all this except

> Red is a warning color

That is definitely the case in western culture, but in places like China, red is a positive color. Always interesting to learn what are universal signifiers (like up for more) and what are culture-specific signifiers!

[hollerith]

Deepseek's iPad app has widgets (buttons labelled "Search" and "DeepThink") that are black in the "off" state and blue to indicate the "on" state.

[throwaway290]

is it why in China drivers run red lights so often? they should really recolor them if what you say is true

[thaumasiotes]

> Blue has best contrast on both white and black backgrounds, and stands out from black.

Why would it matter if it has good contrast on two different backgrounds? If you're changing the color of the background, you can also change the color of the link.

[al_borland]

It’s nice to be able to change between the two most common background colors without needing to develop a whole theme.

In the days before CSS was commonplace, it would also be very annoying to manage.