Twenty Twelve uses class .singular that is not defined in the theme

[TomasM]

In style.css under @media print we find bunch of rules with the class .singular. As far as I know, Twenty Twelve does not generate such body class.

Most likely easiest way to fix it is to append code from Twenty Fourteen to the function that creates extra BODY classes:

if ( is_singular() && ! is_front_page() ) {
		$classes[] = 'singular';
	}

[lancewillett]

Thanks for this report, looks like the CSS is only in the Print media query block.

[jbkkd]

removed 'singular' class as it wasn't in use

[lancewillett]

In 27571:

Twenty Twelve: remove unused singular selectors in print CSS block. Props jbkkd, fixes #26866.