[entropy_]

Use blue, the most common types of color blindness are red-green issues(there's a really tiny percentage that doesn't perceive colors at all but really really tiny. And other than those, nobody has trouble with blue)

Source: I'm colorblind(protanope) and red would definitely be an issue. Android studio, for example, is really annoying for me because the particular red they use for errors is very hard to distinguish from black

[zrm]

That kind of violates the intuitive "red/orange/yellow is alarm, blue/green/black is expected" notion though. What you could do is put ASCII characters in blue and non-ASCII characters in red.

[jessriedel]

Isn't this a general argument against ever using red as a warning? Seems to prove too much.

Especially in this case, where there is unlikely to be a specialized class of scammers who go phishing only for people with red-green colorblindness. So long as browsers implement a feature that stops the phishing in 99% of cases, the scammers will try something else.

[brainfire]

It's an argument against using red as the only warning sign.

Compare to Chrome's https indicator- it turns the "https://" part of the URL green (which I can barely distinguish as different, so it is useless to me) and adds a padlock icon.

Colorblind-friendly graphs might use both color and symbols to distinguish elements.

[lb1lf]

-Tritanopes may beg to differ (regarding the blue not being an issue, that is.)

Significantly less common than red/green deficiency, though - I only know of one more on the island I live on (pop. 15,000 or so)

[entropy_]

Wasn't aware of that one. Significantly fewer people affected though(I think red-green is something like 10% of males)

[lb1lf]

-Yup, the affected population is so small I don't bother suggesting to websites and software publishers that they may want to adapt their colour schemes anymore

Kudos to my employer, though - after some discussion, I was given a small budget and our SCADA GUI frontends now sport colour palettes optimized for deuteranopes, protanopes and tritanopes.

We've got a couple of very grateful feedbacks - and, unsurprisingly, quite a bunch of 'Gee, did you have some colorblind sod do your GUIs? My display looks like a Grateful Dead cover!' from people who've inadvertently messed with accessibility settings...