Twenty Thirteen: fix missing space in selector! Props markmcwilliams, fixes #23652.

git-svn-id: http://core.svn.wordpress.org/trunk@23545 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Thirteen: trim down font properties, props obenland. Fixes #23546.

git-svn-id: http://core.svn.wordpress.org/trunk@23546 1a063a9b-81f0-0310-95a4-ce76da25c4cd