Steps to replicate the issue (include links if applicable):

• Go to undelete a page with some content on a wiki on which you have admin privileges and which has typography support
• Click the preview button
• In a separate tab, open another page on the same wiki (just for comparison)

What happens?:
The page to be undeleted has a noticeably smaller font size compared to the other page

What should have happened instead?: Same size

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):

It looks like both are correctly being set to font-size: var(--font-size-medium); but the previewed page ends up with 14px and the normal page ends up with 16px. The text size switcher says it's always supposed to be small size, but that only really makes sense for the rest of the content on that page at best...?

I can live without a change here, but having different sized preview makes me sad. :(