Hi!
Find this part of the code:
echo( 'height:' . $cas_imgheight .';width:' . $cas_imgwidth . ';" />' );
And add "px" to the end of the height and width values:
echo( 'height:' . $cas_imgheight .'px;width:' . $cas_imgwidth . 'px;" />' );
I will have to fix that in the next version of the plugin.