Change 931967 had a related patch set uploaded (by Cyndywikime; author: Cyndywikime):

[mediawiki/extensions/GrowthExperiments@master] Fix font size and visual display for Structured task save dialog

https://gerrit.wikimedia.org/r/931967

I think this issue is deeper than just the title font size or the button miss-alignment. The size of all interfaces rendered on VE global overlay should be rendered with a relative size of 0.875em. It seems we're altering the relative font-size inheritance to a point where all interfaces have a bigger font. I think this was introduced while working on T281185 in I4ae24664fa477c0a0d688e2a4015d6a3cc50ce4f. Adding a font-size: 1em to a class that is added to the VE global surface is causing unexpected font-size to the rest of overlay elements: RejectionDialog and SaveDialog that I know.

The reason to introduce that font-size is to match the floating buttons expected size:

This could be solved by removing the conflicting class and targeting with something more specific,

.ve-ui-overlay-global .mw-ge-minimizedToolbarDialogButton {
    font-size: 1.1em;
}

although removing the class when no minimized would be event better.

Change 931967 merged by jenkins-bot:

[mediawiki/extensions/GrowthExperiments@master] Fix font size and visual display for Structured task save dialog

https://gerrit.wikimedia.org/r/931967