CSS之垂直水平居中方法

//居中方法1
   position: absolute;
   top: 0;
   left: 0;
   right: 0;
   bottom: 0;
   margin: auto;
    346px;
   height: 56px;

//居中方法2
   position: absolute;
   top: 50%;
   left: 50%;
   transform: translate(-50%, -50%);