[floatingatoll]

That's the 'visited link' color, which indicates that you've visited a given post's link. Posts do not change color based on votes. For posts without a link, reading the post requires still visiting the post's link, so it works out as expected from there.

[frosted-flakes]

No, the actual colour of the text on text-only posts is super light. I read somewhere a while back that it was supposed to discourage people from using it too much.

Here's an example from the front page: https://news.ycombinator.com/item?id=23438930

[floatingatoll]

Ah, thanks for clarifying.