You don't need to use TMS for EXTRA.css.. just put it in the usual one, try adding !important.
.xenOverlay.memberCard .userInfo h3 a {
color: green !important;
}
.xenOverlay.memberCard .userInfo h3 a:hover {
color: blue !important;
}
Also, if you're using Chrome, sometimes it takes a million years for the cache to catch up and display the changes.