此效果涉及到 ：
1. css 画图形
2. css3 动态效果
3. 贝塞尔曲线 用法
<style>
.lds-hourglass {
display: inline-block;
position: relative;
width: 72px;
height: 72px
}
.lds-hourglass:after {
content: " ";
display: block;
border-radius: 50%;
width: 0;
height: 0;
margin: 6px;
box-sizing: border-box;
border: 36px solid #ff8686;
border-color: #ffabab transparent #35999e;
animation: lds-hourglass 1.2s infinite
}
@keyframes lds-hourglass {
0% {
transform: rotate(0);
animation-timing-function: cubic-bezier(.55,.055,.675,.19)
}
50% {
transform: rotate(900deg);
animation-timing-function: cubic-bezier(.215,.61,.355,1)
}
100% {
transform: rotate(1800deg)
}
}
</style>
<div class="lds-hourglass"></div>
扩展：3d转换