.gallery {
  --s: 30px; /* control the zig-zag size */
  
  display: grid;
  height: 350px;
  gap: 8px;
  grid-auto-flow: column;
  place-items: center;
}
.gallery > img {
  width: 0;
  min-width: calc(100% + var(--s));
  height: 0;
  min-height: 100%;
  object-fit: cover;
  --mask: 
    conic-gradient(from -135deg at right,#0000,#000 1deg 89deg,#0000 90deg) 
      100% calc(50% + var(--_p,0%))/51% calc(2*var(--s)) repeat-y,
    conic-gradient(from   45deg at left ,#0000,#000 1deg 89deg,#0000 90deg) 
        0% calc(50% + var(--_p,0%))/51% calc(2*var(--s)) repeat-y;
  -webkit-mask: var(--mask);
          mask: var(--mask);
  cursor: pointer;
  transition: .5s;
}
.gallery > img:nth-child(odd) {
  --_p: var(--s);
}
.gallery > img:hover {
  width: 15vw; 
}
.gallery > img:first-child {
  min-width: calc(100% + var(--s)/2);
  place-self: start;
  --mask: 
    conic-gradient(from -135deg at right,#0000,#000 1deg 89deg,#0000 90deg) 
      0 calc(50% + var(--_p,0%))/100% calc(2*var(--s));
}
.gallery > img:last-child {
  min-width: calc(100% + var(--s)/2);
  place-self: end;
  --mask: 
    conic-gradient(from   45deg at left ,#0000,#000 1deg 89deg,#0000 90deg) 
       0 calc(50% + var(--_p,0%)) /100% calc(2*var(--s));
}

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  align-content: center;
  background: #ECD078;
}