.sandbox{
  padding: 2% 2% 0;
  text-align: justify;
  font-size: 0;
}

.sandbox:after{
  content: '';
  display: inline-block;
  width: 100%;
}

.sandbox .mix,
.sandbox .gap{
  display: inline-block;
  width: 49%;
}

.sandbox .mix{
  text-align: left;
  margin-bottom: 2%;
  margin-right: 1%;
  display: none; /*<-- uncomment this rule for use with MixItUp */
}

.sandbox .mix:before{
  content: '';
  display: inline-block;
  padding-top: 0%;
}

@media all and (min-width: 420px){
  .sandbox .mix,
  .sandbox .gap{
    width: 32%;
  }
}

@media all and (min-width: 640px){
  .sandbox .mix,
  .sandbox .gap{
    width: 23.5%;
  }
}