.gal__container{
    position: relative;
    display: grid;
    grid-gap: 15px;
    width: 80%;
    margin: auto;
    grid-template-columns: 1fr 1fr 1fr;
    grid-template-rows: 150px 150px 150px 150px 150px 150px;
    grid-template-areas: "img1 img2 img3"
                         "img7 img2 img3"
                         "img4 img2 img6"
                         "img4 img9 img8"
                         "img10 img9 img8"
                         "img10 img9 img11";
}

.gal__container .img1 {
    grid-area: img1;
}
.gal__container .img2 {
    grid-area: img2;
}
.gal__container .img3 {
    grid-area: img3;
}
.gal__container .img4 {
    grid-area: img4;
}
.gal__container .img5 {
    grid-area: img5;
}
.gal__container .img6 {
    grid-area: img6;
}
.gal__container .img7 {
    grid-area: img7;
}
.gal__container .img8 {
    grid-area: img8;
}
.gal__container .img9 {
    grid-area: img9;
}
.gal__container .img10 {
    grid-area: img10;
}
.gal__container .img11 {
    grid-area: img11;
}
.gal__container .img12 {
    grid-area: img12;
}
.gal__container .item_gal {
    position: relative;
}
.gal__container .item_gal img{
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: 0.5s;
    border-radius: 10px;
}

.gal__container:hover .item_gal img:not(:hover){
    filter: grayscale(1);
    opacity: 0.7;
}