Math expressions should be centered by default.
I’m not sure what you’re looking for.
You’ll need a CSS snippet to be able to add mathjax blocks as inline code.
Like this? (On my phone screen)
On desktop description & formulae wont break into 2 lines
I see.
If you’re willing to try out my theme, then you can set up centered text blocks and much more. Here’s my wiki page for callouts
By default, my theme doesn’t apply colors, so your background will be white too.
Note, in this screenshots I am using my mermaid theme too.