body{
  margin: 20px;
  padding: 0;
  background-image:url('http://millerxbots.com/images/blacklinen.png');
}

.main{
  display: grid;
  grid-template-columns: repeat(6,1fr);
  grid-auto-rows: 100px 300px;
  grid-gap: 10px;
  grid-auto-flow: dense;
}

.gallery-item{
  width: 100%;
  height: 100%;
  position: relative;
}

.gallery-item .img{
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.gallery-item .img img{
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 50% 50%;
  cursor: pointer;
  transition: .5s ease-in-out;
}

.gallery-item:hover .img img{
  filter: grayscale(100%);
  transform: scale(1.1);
}

.w-1{
  grid-column: span 1;
}
.w-2{
  grid-column: span 2;
}
.w-3{
  grid-column: span 3;
}
.w-4{
  grid-column: span 4;
}
.w-5{
  grid-column: span 5;
}
.w-6{
  grid-column: span 6;
}

.h-1{
  grid-row: span 1;
}
.h-2{
  grid-row: span 2;
}
.h-3{
  grid-row: span 3;
}
.h-4{
  grid-row: span 4;
}
.h-5{
  grid-row: span 5;
}
.h-6{
  grid-row: span 6;
}