.content-top {
width: 1250px;
height: 250px;
margin: 0 auto;
border: 1px solid #171d32;
background-color: rgba(255,255,255,.06);
background-image:url("../images/correcting/lta.png"),url("../images/correcting/lba.png"),url("../images/correcting/rta.png"),url("../images/correcting/rba.png");
background-repeat: no-repeat, no-repeat,no-repeat, no-repeat;
background-position: 0 0, 0 100%, 100% 0, 100% 100%;
}