I just recently noticed that the font color inside the tags behaves like links, which means the font color is the normal dark grey/light black when the corresponding link (i.e. the respective tag page) has not been visited yet. But once you click/visit that tag, it turns into a dark cyan blue font. This happens on the main site and on meta and seems to be a very recent "feature".
Now first of all, I'd like to know if this is a feature at all or just a bug somehwere in the style sheet or whatever. Or maybe this just happens to me (on Firefox 37.0.2).
If it is actually supposed to be a feature, though, then I would question its validity, since it doesn't seem to be relevant if one has ever visited a tag's page and it just results in an inconsistent design for tags which suggests a semantic difference between the tags where there is none. It also seems to rob the tags of the nice contrast their rather greyish color made to the rest of the very cyan-heavy font colors of a questions list.
UPDATE: The same bug/feature seems to apply to those little light grey "modified/answered/asked X hours ago" thingies under the question title in the questions list, too. And as it is for tags, this different coloring is equally unnecessary and distracting there, too.