This applies to the Classic email design only.
Yes! Centering an email is very easy with CSS.
By default, Buttondown's emails are constrained in width and left-aligned. This is because we find that left-aligned text is readable, legible and scans easily.
But if you want a center-aligned email, we won't begrudge you! Just apply the following rule in your design settings:
This will keep the text in your email left-aligned, but center the text in the browser. Here's what this looks like: