In:

includes/templates/responsive_apparel_boutique/templates/tpl_modules_mobile_categories_tabs.php (line 25)
includes/templates/responsive_apparel_boutique/common/tpl_header.php (line 97)

you used the PHP invocation shorthand of "<?" which caused unparsed PHP to be printed in my header. I changed those to "<?php" and all was well. Using the shorthand requires a setting in php.ini which not all people will have, so the formal invocation is recommended.