XF 1.5 How to center the description messages category ?

[Reaks Lobby]

Good evening, I want to know how to center the description of message category ?
Thank you
Best regards

Screen : http://prntscr.com/8qmtab
Excuse me for my english

 

[Amaury]

.thread_view #pageDescription {
    text-align: center;
}

 

[Reaks Lobby]

.thread_view #pageDescription {
    text-align: center;
}

Its always make the same ... No one to help me ?

 

[Reaks Lobby]

Fixed by Me