img {
    width: 100%;
    border-radius: 60px;
    border: 10px solid white;
}

#contenedor {
    display: flex;
    flex-direction: row;
    justify-content: space-evenly;
}

#contenedor .columna {
    display: flex;
    flex-direction: column;
    flex-basis: 30%;
}

#contenedor .columna .img{
    display:inline-block;
    position:relative;
}

#contenedor .columna img:hover {
    border: 10px solid black;
    filter: grayscale(90%);
    opacity: 0.30;
}

#contenedor .columna .img .mensaje {
    position: absolute;
    font-size: 3rem;
    font-weight: bold;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    z-index:-1;
    margin: auto;
}