I figured it out... in case anyone needs it...
Code:
.smartBG_0 #logo {background-image: url(../images/smartbg_0.png);background-size:100%;}
.smartBG_1 #logo {background-image: url(../images/smartbg_1.png);background-size:100%;}
.smartBG_2 #logo {background-image: url(../images/smartbg_2.png);background-size:100%;}
.smartBG_3 #logo {background-image: url(../images/smartbg_3.png);background-size:100%;}
.smartBG_4 #logo {background-image: url(../images/smartbg_4.png);background-size:100%;}