#grid-container {
  width: 100%;
  overflow: hidden; 
}

.grid-item {
  opacity: 0;
  float: right;
  box-sizing: border-box;
  border-right:3px solid #fff;
  border-bottom:3px solid #fff;
}

.grid-item img {
  width: 100%;
  height: 100%;
  
}

.grid-item.loaded {
  opacity: 1;
  transition: opacity .5s;
}