G183: 4.5:1 in headline of example 1, 5:1 in the example

[JAWS-test]

headline example 1:

Colors that would provide 3:1 contrast with black words and 4.5:1 contrast with a white background

linked example 1:

The following 26 web-safe colors pass at 3:1 vs black and 5:1 vs. white.

What explains the difference between 4.5:1 and 5:1? 4.5:1 would be the requirements from SC 1.4.3. Is 5:1 a typo or deliberately chosen to ensure better visibility of the links?

• If typo: Then had to check on fix if more colors are added if 4.5:1 instead of 5:1 is the limit.
• If on purpose: Then this should be explained. And besides, then e.g. 6:1 would be much better to distinguish the links.

Actually, it would be good to point out in the example that this only satisfies 1.4.3 and not 1.4.6. It can also be pointed out that AAA conformance cannot be achieved with G183, since there is no web-safe color that has 7:1 to the white background and 3:1 to the black text.

By the way: Do the web-safe colors still have any relevance today? Or do not all devices display all colors correctly, regardless of whether web-safe or not?