.corner{
    position:absolute;

    width:120px;
    height:120px;
}

.top-left{
    top:30px;
    left:30px;

    border-top:2px solid #37BABA;
    border-left:2px solid #37BABA;
}

.top-right{
    top:30px;
    right:30px;

    border-top:2px solid #37BABA;
    border-right:2px solid #37BABA;
}

.bottom-left{
    bottom:30px;
    left:30px;

    border-bottom:2px solid #37BABA;
    border-left:2px solid #37BABA;
}

.bottom-right{
    bottom:30px;
    right:30px;

    border-bottom:2px solid #37BABA;
    border-right:2px solid #37BABA;
}