小さいアイコンボタン（回転その2）

html

<div class="flex">
<a class="btn" href="#"><i class="material-icons icons">room</i></a>
<a class="btn" href="#"><i class="material-icons icons">play_arrow</i></a>
<a class="btn" href="#"><i class="material-icons icons">call</i></a>
<a class="btn" href="#"><i class="material-icons icons">add</i></a>
</div>

css

.flex{
  display: flex;
  display: -moz-flex;
  display: -o-flex;
  display: -webkit-flex;
  display: -ms-flex;
  flex-direction: row;
  -webkit-flex-direction: row;
  flex-wrap:wrap;
}

.btn {
  display: block;
  width: 50px;
  height: 50px;
  margin:5px;
  background: #ff77bd;
  text-align: center;
  border-radius: 50%;
  transition: 0.5s;
  -webkit-transition: 0.5s;
  box-shadow: 0 3px 3px 0 rgba(0, 0, 0, 0.7);
}

.icons{
  display:block;
  line-height: 50px;
  vertical-align: middle;
  font-size: 30px;
  color:#FFF;
  transition: 0.8s;
}

.btn:hover{
  transform: rotateY(180deg);
  -webkit-transform: rotateY(180deg);
}