switch-divi-mobile-logo.css

/* Switch Divi Logo on Mobile Devices */
@media only screen and (max-width: 981px) {
#logo {
content: url(“http://mydomainname.com/wp-content/.../MyMobileLogo.png”);
max-height: 160px;
height: auto; /* default value - the browser calculates the height */
}
}

/* Restrict the width of the logo if necessary */
@media (max-width: 981px){
.et_header_style_left #logo{
max-width: 75%;
}
}