用 radial-gradient 偽元素畫出雪山裝飾

.scene .mountain .snow::after {
  content: "";
  position: absolute;
  top: 99px;
  left: -80px;
  width: 160px;
  height: 15px;
  background-image: radial-gradient(
    circle at 10px 15px,
    #3fae4a 12px,
    transparent 13px
  );
  background-repeat: repeat;
  background-size: 20px 20px;
  transform: rotateX(180deg);
}