System.gui.confirm() Message Formatting

How can format the position and styles of the text in a system.gui.confirm() textbox?
I’ve got the box so it displays a custom message, but how can I center the message?

It will accept HTML tags for the message, but the centering is a little different than you would think.
Both of these are using the <center> tag

Exactly what I was looking for. Adding at few non-breakable spaces &nbsp; to the front of each newline helps center it better (for my message anyway)