关键兼容代码：
display: -webkit-box; display: -webkit-flex; display: -moz-box; display: -moz-flex; display: -ms-flexbox; display: flex; /* 水平居中*/ -webkit-box-align: center; -moz-box-align: center; -ms-flex-pack:center;/* IE 10 */ -webkit-justify-content: center; -moz-justify-content: center; justify-content: center;/* IE 11+,Firefox 22+,Chrome 29+,Opera 12.1*/ /* 垂直居中 */ -webkit-box-pack: center; -moz-box-pack: center; -ms-flex-align:center;/* IE 10 */ -webkit-align-items: center; -moz-align-items: center; align-items: center;
