There isn't an explicit class for "read" threads, only "unread" threads. But you can style all threads and then override that style for unread threads. For example:
Admin CP -> Appearance -> Templates -> EXTRA.css
Add this code:
Code:
.discussionListItems .title a
{
color: red;
}
.discussionListItems .unread .title a
{
color: blue;
}
Now "read" threads will be red and "unread" threads will be blue.
Will this address the thread titles, the usernames, and the link in the lower right hand corner? I cannot seem to find the place in the style editor to address these directly or all at once. Is extra.css the only way to go?