.box-login { -ms-flex-align: center; align-items: center; background: #0148b9; display: -ms-flexbox; display: flex; -ms-flex-direction: column; flex-direction: column; height: 100vh; -ms-flex-pack: center; justify-content: center; position:relative; overflow:hidden; width: 100%; } .box-login:before{position:absolute;width:1200px;height:1200px;top:calc(50% - 600px);left:50%;margin-left:-600px;content:"";background:transparent url(../images/trongdong.png) no-repeat center center;background-size:100% auto;opacity:.3} .box-login:before{-webkit-animation-name:rotate;-webkit-animation-duration:60s;-webkit-animation-iteration-count:infinite;-webkit-animation-timing-function:linear;-moz-animation-name:rotate;-moz-animation-duration:60s;-moz-animation-iteration-count:infinite;-moz-animation-timing-function:linear} @-webkit-keyframes rotate{ from{-webkit-transform:rotate(0)} to{-webkit-transform:rotate(360deg)} } @-moz-keyframes rotate{ from{-moz-transform:rotate(0)} to{-moz-transform:rotate(360deg)} }