This seems to be a simple oversight in the chat style sheet. The following extra rule should fix it:
.ob-post-tags a:hover, .ob-user-tags a:hover { text-decoration: none }
I'll include this fix in the next release (v1.8) of SOUP, if it doesn't happen to get fixed before that.
Edit: SOUP 1.8 is out now, and includes this fix.
However, it turns out that, while the CSS fix above works fine for tags inside post / user oneboxes, it doesn't stop the same bug from happening with tags manually included in chat messages.
Alas, there doesn't seem to be any easy way to fix this using CSS. The problem is that the HTML markup for tags in chat currently looks like this (line breaks and indentation added):
<a href="http://meta.stackexchange.com/questions/tagged/chat">
<span class="ob-post-tag" style="background-color: #E7E7E7;
color: #6F6F6F; border-color: #6F6F6F; border-style: solid;">
chat
</span>
</a>
Since parent selectors are not yet part of any current CSS standard (or browser feature set), there's no good way to select those <a>
tags for styling without also affecting all other links in chat. The closest I can get is something like a[href*="/questions/tagged/"]
, but that'll also match any URLs to tag pages someone might post in chat without using the actual tag syntax. Fixing this in JavaScript isn't so easy, either, since the SE chat implementation provides no easy way for third-party code to tell when new messages are received.
(Actually, while writing this, I thought of an ugly way to do this "at the last minute" using jQuery mouse event delegation. If it works, I may include it in the next SOUP release.)