Bring the install/update screens in line with the new admin design. This affects:

* Creating a wp-config.php file
* Installation
* Database upgrade
* Database repair
* Readme.html
* Network sites actions

What's changed:

* Bring background/text/link/border colours in line with mp6
* Bring fonts in line with mp6 (see note below)
* Switch to device-width for the viewport and tweak margins etc so the layout works nicely on all device sizes
* Switch to the new vector WordPress logo in the header to match the log in screen
* Force table cells into rows in the <782px media query

Fixes #25951, props johnbillion.


Built from https://develop.svn.wordpress.org/trunk@26298


git-svn-id: http://core.svn.wordpress.org/trunk@26203 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update error screens with the new visual design:

* Bring in new styles for backgrounds/text/link/borders/buttons
* Switch to device-width for the viewport and tweak margins etc so the layout works nicely on all device sizes

Fixes #25956, props johnbillion.


Built from https://develop.svn.wordpress.org/trunk@26299


git-svn-id: http://core.svn.wordpress.org/trunk@26204 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Switch to a fluid padding-top on #login so it aligns nicely on small screens. Fixes #26130.
Built from https://develop.svn.wordpress.org/trunk@26300


git-svn-id: http://core.svn.wordpress.org/trunk@26205 1a063a9b-81f0-0310-95a4-ce76da25c4cd