点击按钮平滑回到顶部

html：

<!--Scroll to top-->
<div id="scroll-to-top" class="scroll-to-top">
	<span class="icon ion-ios-arrow-up"></span>
</div>

　　

css:

.scroll-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  z-index: 999;
  height: 40px;
  width: 40px;
  background: #655E7A;
  border-radius: 50%;
  text-align: center;
  line-height: 40px;
  color: white;
  cursor: pointer;
  transition: 0.3s;
  display: none;
}

　　

@media (max-width: 480px) {
  .scroll-to-top {
    bottom: 15px;
    right: 15px;
  }
}

　　鼠标悬浮按钮变色

.scroll-to-top:hover {
  background-color: #333;
}