Hello,
As I see your header is shown fine:
http://storage1.static.itmages.com/i/15/0602/h_1433232880_8261785_f83880b973.png
Concerning the responsiveness add this code in custom.css file:
@media (max-width: 780px) {.header {
background-image: url("http://hersbridaltest.jk-design.com.au/wp-content/themes/legenda/images/header.png") !important;
background-attachment: inherit;
background-position: top left !important;
background-size: 100% 50%;
background-repeat: no-repeat;
}}
Regards,
Eva Kemp.