鼠标移上去触动hover致使div向上移动几个相素（动画transition轻轻的移动）

.box{
		transition: all 0.2s linear 0s;
    bottom: 0px;
}
.box:hover{
    box-shadow:0px 0px 8px #ccc;
    position: relative;
    bottom: 4px;
 }