I think it should be placed inside the @media only screen and (max-width: 767px) section targeting .header-image .site-title a but I really don’t know what should I put in here. Maybe background-image property?
I have uploaded an image into images folder called cabecera320.png but don’t know how to use it!!!
Of course I would love to be added to your showcase but I need to finish all the work in here. Thanks for your help!! I really appreciate it.