*, *:before, *:after{
    padding:0;
    margin: 0;
    outline: 0;
    box-sizing: border-box;
}
.encabezado{
    text-align: center;
    padding: 20px 0;

}
.galeria{
    display: flex;
    flex-wrap: wrap;
    padding: 10px 20px;
}
.columna{
    flex: 25%;
    max-width: 25%;
    padding: 0 4px;
}
.columna img{
    margin-top:8px;
    vertical-align: middle;
    width: 95%;
   /* filter:grayscale(100%);*/
    transition: all .3s ease;
}
.columna img:hover{
    cursor: pointer;
    filter: grayscale(0%);
    box-shadow: 0 0 10px rgba(0,0,0,0.5);
    transform: scale(1.1);
}
.overlay{
    position:fixed;
    left: 0;
    top: 0;
    width: 100vw;
    height: 100vh;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 10000;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: all .7s ease;
    visibility: hidden;
    opacity: 0;
}
.overlay .slideshow{
    width: 90%;
    height: 90%;
    background-color: rgba(255, 255, 255, .9);
    color:#000;
    position: relative;
    display: flex;
    justify-content: center;
    padding: 20px 20px;
}
.slideshow img{
    height: 100%;
    width: 100%;
    object-fit: contain;
}
.btn_cerrar{
    position: absolute;
    top: -15px;
    right:-15px;
    font-size: 35px;
    background-color: rgba(0, 0, 0, .7);
    color: #fff;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 5px;
    transition: all .2s ease;
}
.btn_cerrar:hover{
    cursor: pointer;
    transform: scale(1.2);
}
.botones{
    width: 70px;
    height: 70px;
    border-radius: 50%;
    color: #000;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 70px;
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    cursor: pointer;
    color: rgb(74, 74, 74);
}
.botones:hover > i{
    transform: scale(1.1);
    transition: all .2 ease;
}
.atras{
    left: 20px;
}
.adelante{
    right: 20px
}
.mdi{
    pointer-events: none;
}
@media screen and (max-width: 800px){
    .columna{
        flex: 50%;
        max-width: 50%;
    }
    .botones{
        font-size: 55px;
    }
    .atras{
        left: 5px;
    }
    .adelante{
        right: 5px;
    }
    .slideshow img{
        width: 80%;
    }
}

@media screen and (max-width: 600px){
    .columna{
        flex: 100%;
        max-width: 100%;
    }
    .overlay .slideshow{
        width: 90%;
        height: 50%;
        background-color: rgba(255, 255, 255, .9);
        color:#000;
        position: relative;
        display: flex;
        justify-content: center;
        padding: 10px 10px;
    }
}