Minor copy updates. Update heading style, text size, spacing in smaller columns. Remove columns placement code to simplify CSS. This was necessary for IE11, but modern browsers can use auto-placement. Move navigation out of the banner to keep size & background placement consistent across About section.
Props marybaum, sereedmedia, annezazu, jpantani, laurlittle, richtabor, markoserb, fcoveram, joen, kebbet.
See #57477.
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git-svn-id: http://core.svn.wordpress.org/trunk@55031 1a063a9b-81f0-0310-95a4-ce76da25c4cd
