html, body {
  height: 100%;
  margin: 0; }

main.grid {
  column-width: 260px;
  /* target column width; browser decides how many fit */
  column-gap: 8px;
  padding: 8px; }

main.grid img {
  width: 100%;
  height: auto;
  /* natural aspect ratio */
  display: block;
  margin: 0 0 8px;
  break-inside: avoid;
  /* prevent image from splitting across columns */ }