为什么梯度不出现在heroku上,即使带有厂商前缀?

button {
  background-image: -moz-linear-gradient( -135deg, rgb(255, 131, 10) 0%, rgb(255, 198, 54) 100%);
  background-image: -webkit-linear-gradient( -135deg, rgb(255, 131, 10) 0%, rgb(255, 198, 54) 100%);
  background-image: -ms-linear-gradient( -135deg, rgb(255, 131, 10) 0%, rgb(255, 198, 54) 100%);
  color: #ffffff;
  font-size: 2em;
  border-radius: 999px;
  width: 19%;
  height: 6vh;
  border: #ffffff 2px solid;
  outline: none;
  transition: all 2s cubic-bezier(0.075, 0.82, 0.165, 1);
  cursor: pointer;
}