BLUEMARINE THEME:

img[src$="files/bluemarine_logo.png"] {
width: 0 !important;
height: 115px !important;
padding-left: 340px !important;
background: url("YOUR IMAGE LINK GOES HERE") center center no-repeat !important;
}


DECO THEME:

img[src$="files/deco_logo.png"] {
width: 0 !important;
height: 115px !important;
padding-left: 340px !important;
background: url("YOUR IMAGE LINK GOES HERE") center center no-repeat !important;
}


NOTE: MODIFICATION OF THESE VALUES MAY BE NECESSARY (TO FIT YOUR IMAGE PROPERLY):

height: 115px !important;
padding-left: 340px !important;