.header-slider .ba-slideshow-caption:before {
    border: 10px solid rgba(89, 197, 112, 0.5);
    content: "";
    height: 300px;
    left: 50%;
    position: absolute;
    top: 50%;
    transform: translate(-50%, -50%) rotate(45deg);
    -webkit-transform: translate(-50%, -50%) rotate(45deg);
    width: 300px;
    z-index: -1;
}