CSS tweaks, update About page

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.