background: url('/assets/images/offers/key.png') bottom 30px right 0 no-repeat, url('/assets/images/offers/sell.png') bottom right no-repeat #F7F7F9;
.class {
background:
url('/assets/images/offers/key.png') bottom 30px right 0 / 50% no-repeat,
url('/assets/images/offers/sell.png') bottom right no-repeat #F7F7F9;
}
.class {
background:
url('/assets/images/offers/key.png'),
url('/assets/images/offers/sell.png') #F7F7F9;
background-position: bottom 30px right 0, bottom right;
background-size: 50%, auto;
background-repeat: no-repeat;
}
bg-size
Смотри background-size. Это свойство должно быть указано после background-position, разделенного символом '/'.
MDN