div不定宽高的居中方式
方法1:
position:absolute; top:50%; left: 50%; -webkit-transform: translate(-50%, -50%); transform: translate(-50%, -50%);
方法2:
display: flex; align-items: center; justify-content: center;
方法3:
.parent-panel2:after{ content:""; display: inline-block; vertical-align: middle; height: 100%; }
定宽度
position:absolute; top:50%; left:50%; margin-top:(width/2); margin-left:(width/2);