None of Calendar has been designed yet, this is intentional given it's a fast moving prototype. I have a cut in my dev environment, but don't expect to see it for a few weeks.

OK - those screenshots were taken of secure.phabricator.com's calender instance - are there incoming updates for the UI there?

It only matters is that Calendar is a prototype application, and we prefer not to take bug reports on prototypes since they slow down the development process: https://secure.phabricator.com/book/phabricator/article/prototypes/

In this case, that header doesn't exist in the final UI.

Ah I'm sorry about that, will remember.