CSS动画 防止动画结束后，回归原位

animation-fill-mode防止动画结束后，回归原位

animation: arrowsfirst 1s;
animation-timing-function: linear;
animation-fill-mode: forwards;
-webkit-animation: arrowsfirst 1s; /* Safari and Chrome */
-webkit-animation-timing-function: linear;
-webkit-animation-fill-mode: forwards;