.gallery {
    --s: 150px; /* control the size */
    --g: 10px;  /* control the gap */
    --f: 1.5;   /* control the scale factor */
    
    display: grid;
    gap: var(--g);
    width: 95%;
    aspect-ratio: 1;
    grid-template-columns: repeat(3,auto);
  }
  
  .gallery > img {
    width: 0;
    height: 0;
    min-height: 100%;
    min-width: 100%;
    object-fit: cover;
    cursor: pointer;
    filter: grayscale(50%);
    transition: .35s linear;
  }
  
  .gallery img:hover{
    filter: grayscale(0);
    width:  calc(var(--s)*var(--f));
    height: calc(var(--s)*var(--f));
  }