.back-btn .back-btn__inner::before {
  background: url(//levi.jp/cdn/shop/t/3/assets/n-btn-arrow.svg?v=121882363100453753381740121537) center no-repeat;
  background-size: contain;
}
@media (min-width: 750px) {
  .back-btn .back-btn__inner:hover::before {
    background: url(//levi.jp/cdn/shop/t/3/assets/n-btn-arrow-b.svg?v=62287244715039130851740121536) center no-repeat;
  }
}