CSS tweaks, update About page breaks

* Add hyperlink color.
* Bold link title rather than the whole line.
* Link titles are lighter.
* Underline tag line hyperlinks on-hover.
* Decrease tag line margins.
* Change visited links to violet.
* Button shadows are more subtle.
* Even the padding in link markdown.
* Sidebar titlebox borders are lighter.
* Link markdown box is lighter.
* Moderator list is a shaded box.
* Change line breaks to paragraph tags for About page.