#gallery {
  line-height:0;
  -webkit-column-count:5; /* split it into 5 columns */
  -webkit-column-gap:5px; /* give it a 5px gap between columns */
  -moz-column-count:5;
  -moz-column-gap:5px;
  column-count:5;
  column-gap:5px;
}

#gallery img {
  width: 100% !important;
  height: auto !important;
  margin-bottom:5px; /* to match column gap */
}

@media (max-width: 1200px) {
  #gallery {
   -moz-column-count:    4;
   -webkit-column-count: 4;
   column-count:         4;
  }
}

@media (max-width: 1000px) {
  #gallery {
   -moz-column-count:    3;
   -webkit-column-count: 3;
   column-count:         3;
  }
}

@media (max-width: 800px) {
  #gallery {
   -moz-column-count:    2;
   -webkit-column-count: 2;
   column-count:         2;
  }
}

@media (max-width: 400px) {
  #gallery {
   -moz-column-count:    1;
   -webkit-column-count: 1;
   column-count:         1;
  }
}