Be specific about .date-and-tags font.

Otherwise, e.g. Safari and Chrome will pick different fonts for
"monospace" with different perceived sizes.
Use new .read-more class.
New <body> font.

Also, reduce <code> font size a bit, since the perceived size of the
new body font is a bit smaller.
Regenerate using latest Frog: New text/style for "read more" links.