phone.css

.banner {
  width: 10rem;
  height: 15.98rem;
  background: url(../images/banner.png) no-repeat;
  background-size: 100% 100%;
  position: relative;
  margin: 0 auto;
}
.banner .btn {
  width: 4.65rem;
  height: 1.5rem;
  position: absolute;
  top: 13.7rem;
  left: 2.7rem;
}