Related to displaying list subscribe in registration form (regacymailing plugin) on the mobile layout, I would suggest taking out nowrap="nowrap" from lines 588 and 592. If it's on, the long titles are forced to being displayed on the entire row, making it unresponsive.
Maybe, for the future version of this plugin, it would be a good idea to simplify the table structure and use some simplified divs.
Also, adding the CSS to header should be made via addStyleDeclaration, not by $body = preg_replace('#</head>#', $stylestring.'</head>', $body, 1); (line 706), as this method creates two <style> sections in the head instead of only one.
