Splitting out from Eric's comment to solve T345308 and future users of Codex dialogs.
Acceptance criteria
- Vector: Body styles are applied to teleported elements, so far only dialogs
- Vector legacy: Body styles are applied to teleported elements, so far only dialogs
- Minerva: Body styles are applied to teleported elements, so far only dialogs
Notes
The skin body styles live in different less files (typography and screen). We could add the vector-body class to the teleport target element or split body styles into mixins and reuse them in skinStyles/mediawiki.page.ready.less.