DFW:
- Move the word count and "Just Write" to a fixed bar at the bottom.
- Fix responsive mode to 480px. Narrower screens will have a scroll bar.
- Hide the Help button on screens < 480px, move the Save button to the right, make it bigger to match the others, and other responsive mode fixes.
Fixes #26907, see #27709
Built from https://develop.svn.wordpress.org/trunk@28043


git-svn-id: http://core.svn.wordpress.org/trunk@27873 1a063a9b-81f0-0310-95a4-ce76da25c4cd