.bt_quote_icon {
    background-image: url(vc_icon.png);
}

.bt_quote_icon_item {
    background-image: url(vc_icon_item.png);
}

.bt_quote_icon_multiply {
    background-image: url(vc_icon_multiply.png);
}

.bt_quote_icon_group {
    background-image: url(vc_icon_group.png);
}