sebelum

#front_side {
    background: url(<?php echo SWB.'files/membercard/old/'.$sysconf['print']['membercard']['front_side_image'] ?>) center center;
  }

  #back_side {
    background: url(<?php echo SWB.'files/membercard/old/'.$sysconf['print']['membercard']['back_side_image'] ?>) center center;
  }

Sesdudah

#front_side {
  background-image: url(<?php echo SWB.'files/membercard/old/'.$sysconf['print']['membercard']['front_side_image'] ?>);
  background-position: center center;
  background-repeat: no-repeat;
  background-size: 100% 100%;
}

#back_side {
  background-image: url(<?php echo SWB.'files/membercard/old/'.$sysconf['print']['membercard']['back_side_image'] ?>);
  background-position: center center;
  background-repeat: no-repeat;
  background-size: 100% 100%;
}