At the moment, questions at the front page can be told apart as follows:
Questions with no answer (at SO: "0 answers"; red);
Questions with at least one answer, but no accepted one (at SO: "[number] answer(s)"; white on green);
Questions with an accepted answer (at SO: "[number] answer(s); yellow on green).
With this color scheme, one can not discern questions without upvoted or accepted answers (i.e, those that are considered "unanswered"). I originally suggested the following amendment to the color scheme:
- Questions with at least one answer, but no upvoted or accepted one (at SO: "[number] answer(s)"; light red on green).
Here's how it would have looked like at SO (old v. original proposal):
But as Flexo has pointed out in his answer, "the use of colour is already non-intuitive, don't make it worse by introducing more unintuitive colours". I therefore now suggest to simply assign the existing color/shape scheme for questions with no answers to all "unanswered" questions (here's old v. new):
This alternative proposal should be very easy to implement across all SE sites because there's no need to augment each site's design with a new frontpage color/shape scheme.