mvpin this field, you'll be able to define following css clases to customise how user's belonging to this rank are presented:
list-group-rank-mvpclass will be added to rows in user rankings with users with this rank.
page-header-rank-mvpclass will be added to page header on profiles of users with this rank.
post-mvpclass will be added to posts made by users with this rank.
user-card-mvpclass will be added to user cards presenting users with this rank.