.laboratoire__item {
    position: relative;
    cursor: pointer;
    overflow: hidden;
}

.laboratoire__mask {
    margin:0;
    border-radius:20px;
    position: absolute;
    top:0;
    left:0;
    width:100%;
    height:100%;
    background: rgba(0,0,0,0.5);
    color: #fff;
    font-weight: 700;
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    transition: opacity 0.3s;
    pointer-events: none;
    text-transform: uppercase;
}

.laboratoire__item:hover .laboratoire__mask {
    opacity: 1;
}