This is the code which helps expand and reduce the maps size and makes it responsive.
$("#content").fitVids({ customSelector: "iframe[src^='http://maps.google.com/']"});
$("#content").fitVids({ customSelector: "iframe[src^='https://maps.google.com/']"});
and it is located in js/main.js at line number 412. Can you try the following additional code and see if that helps –
// Take care of maps too - https://github.com/davatron5000/FitVids.js - customSelector option
$("#content").fitVids({ customSelector: "iframe[src^='https://www.google.com/maps/']"});
$("#content").fitVids({ customSelector: "iframe[src^='http://www.google.com/maps/']"});
It did help me for another theme and it should work provided your maps is within the #content element. Google changed the URL of maps recently and hence the above change.