如何在降价时显示双下划线？

<div class="sale-price">
  <span class="original-price">原价：¥100</span>
  <span class="discounted-price">降价：¥80</span>
</div>

.sale-price {
  display: inline-block;
}

.original-price {
  text-decoration: line-through;
}

.discounted-price {
  font-weight: bold;
  text-decoration: underline;
}