让百分比的布局元素居中

center.css

.wrap{
width:50%;
height:300px;
positon:relative;
}
.center{
position: absolute;
top: 50%;
left: 50%;
width:50%;
height:30%;
padding:20px;
text-align:center;
background:#393;
color:#fff;
transform: translate(-50%, -50%);
}