Currently there are several instances of .errorbox scattered in
- MobileFrontend/resources/mobile.messageBox.styles/messageBox.less
- MobileFrontend/resources/mobile.special.styles/common.less
- MinervaNeue/resources/skins.minerva.base.styles/ui.less
- MinervaNeue/skinStyles/mediawiki.special.userlogin.common.styles/minerva.less
and somewhat related .error treatment, that actually should be an error box in
- MobileFrontend/resources/mobile.talk.overlays/talk.less
It seems unnecessarily complex to have those separated.
Also, .error should be used for inline error messages and .errorbox for error block messages and adhere to the standard treatment represented in OOUI's MessageBox.