how to setting the align text?

i cannot to setting align text to my post, i have to tried [center]..[/center] and <center>..</center> but doesnt work.
help me pleasss...

copy paste from gitter:

the center tags are old
you can use custom css in your flarum
and just do text-align: center
for instance for the post content:

.Post-body { text-align: center; }