MarkBlocked strikes out usernames that have been blocked. It is modified in order to be compatible with AjaxRC.
You can use window.mbTempStyle and window.mbIndefStyle to customize the username link styles. window.mbTempStyle is for usernames that are blocked temporarily, and window.mbIndefStyle are for those who are blocked indefinitely.
These are the default settings, which is loaded automatically when custom settings are not defined:
window.mbTempStyle = 'opacity: 0.7; text-decoration: line-through'; window.mbIndefStyle = 'opacity: 0.4; font-style: italic; text-decoration: line-through';