Hi Alison
There is a number of ways this can be done but we will try with an all CSS solution first. Could you try adding the following to the Custom CSS field of your templates parameters where # is the URL to your new image...
@media only screen and (max-width: 767px) {
.logo img {
display: block;
-moz-box-sizing: border-box;
box-sizing: border-box;
background: url(#) no-repeat;
width: 180px; /* Width of new image */
height: 80px; /* Height of new image */
padding-left: 180px; /* Equal to width of new image */
}
}
Ciarán