.masonry {
  column-gap: 12px;
  column-width: 260px;   /* browser picks 4/3/2/1 automatically */
  padding: 0;
}

.masonry > * {
  break-inside: avoid;
  -webkit-column-break-inside: avoid;
  page-break-inside: avoid;
  margin: 0 0 12px 0;
}

.masonry img {
  width: 100%;
  height: auto;
  display: block; 
/*  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
*/
  border-radius: 6px;   /* optional */
  box-shadow: 0 0 4px rgba(0,0,0,0.25); /* optional */
}