Update `embedded.png` after running `grunt imagemin`.

After [30059] and [30079] we still had four images which could be minified. Three of them are handled by [30562], the last one by this.

fixes #30141.

git-svn-id: https://develop.svn.wordpress.org/trunk@30563 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: a shorter header on small screens when there is no header text or header image looks more correct.

Props iamtakashi, fixes #30326.




git-svn-id: https://develop.svn.wordpress.org/trunk@30564 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: pinching to zoom in on landscape on iPads is breaking the layout with the sticky sidebar. Providing a one-column view on those screens looks good and will likely prevent other bugs we don't even know about.

Props iamtakashi, fixes #30366.




git-svn-id: https://develop.svn.wordpress.org/trunk@30565 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: prevent too-wide tables from popping out of posts.

Props iamtakashi, fixes #30420



git-svn-id: https://develop.svn.wordpress.org/trunk@30566 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: remove unneeded custom header admin callbacks.

Props philiparthurmoore, fixes #30432.



git-svn-id: https://develop.svn.wordpress.org/trunk@30567 602fd350-edb4-49c9-b593-d223f7449a82