.reference-controls {
    position: absolute;
    top: 52%;
    /* display: flex; */
    justify-content: space-between;
    z-index: 11;
    width: 100%;
}

.reference-controls a,
.reference-controls a:visited {
    display: inline-block;
    transition: .3s opacity;
    position: absolute;
}

.reference-controls a:hover {
    opacity: 0.85;
}

.reference-controls__link-left,
.reference-controls__link-left:visited {
     left: 0;
}

.reference-controls__link-right,
.reference-controls__link-right:visited {
     right: 0;
}

.reference-controls__img {
    height: auto;
    width: 30px;
}

@media (min-width: 768px) {
    .reference-controls__img {
        width: auto;
    }
}

@media (min-width: 768px) {
    .reference-controls {
        top: 51%;
    }
}