http://t.zoukankan.com/1wen-p-4527667.html
.tf-center{
position: fixed;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
-webkit-transform: translate(-50%, -50%);
-moz-transform: translate(-50%, -50%);
-o-transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
}标签：居中,moz,50%,transform,弹框,translate,方法 From： https://www.cnblogs.com/s1ihome/p/16952989.html