The UX team including @Bojhan, @yoroy and others redesigned the content creation screens for D8. Part of that process involved “updating and expanding the visual language of the Seven admin theme“ to express the new interaction design and layout.
Some of the changes will need to apply throughout Seven, and are not specifically tied to the content creation screen. The goal of this issue is to come to an agreement on how to implement those wider changes and then get cracking in collaboration with those working on the content creation screen and with the Mobile Initiative.
Please note: this is an implementation issue. Implementors will likely have questions about design decisions, but let's keep that really brief. Discussing a re-design isn’t part of this issue.