This is caused by rMW441e12f2d9c8: Messages collected above the form are meant to live as boxed messages, which removed the CSS that made them look right :(

There are two ways we could fix this:

• Restore that CSS (easy)
• Make field errors/warnings use .errorbox/.warningbox, like that patch did for the errors/warnings for the entire form (a bit harder, but maybe the right thing to do)

The code that generates these lives in HTMLFormField.php formatErrors() and in mediawiki.htmlform.checker.js. Changing it would affect all non-OOUI forms, including the legacy ones not using WMUI ("VForm") styling.

.mw-htmlform-invalid-input is only defined once. As

.mw-htmlform-invalid-input td.mw-input input {
	border-color: #d33;
}

which makes me think, we should probably remove it and use general error class or move it back to mediawiki.legacy.shared, where it came from Idcd20b4a77

The styling needs to follow inline message styles.

In general displayFormat 'table' seems not to be used widely any more. Maybe it's time to deprecate it and remove, given that it's bad for responsive layout and accessibility. Currently found in

• CentralUser
• CentralCheckUser and
• OAuth/frontend/specialpages/SpecialMWOAuth.php

Every other format, 'div' (although I couldn't find a use case), 'vform' or 'ooui' would be preferable.

Change 581732 had a related patch set uploaded (by Bartosz Dziewoński; owner: Bartosz Dziewoński):
[mediawiki/core@master] Use errorbox/warningbox for all HTMLFormField errors

https://gerrit.wikimedia.org/r/581732

Change 581732 merged by jenkins-bot:
[mediawiki/core@master] Use errorbox/warningbox for all HTMLFormField errors

https://gerrit.wikimedia.org/r/581732

Change 703860 had a related patch set uploaded (by Bartosz Dziewoński; author: Bartosz Dziewoński):

[mediawiki/extensions/GrowthExperiments@master] Update styles for create account form warning

https://gerrit.wikimedia.org/r/703860

Change 703860 merged by jenkins-bot:

[mediawiki/extensions/GrowthExperiments@master] Update styles for create account form warning

https://gerrit.wikimedia.org/r/703860