.square-holder {
  padding:30px;
  border: 1px solid #cecece;
  align-items: center;
  display:flex;
  align-items: center;
  justify-content: center;
  margin-bottom:20px;
  background-color:#f1f1f1;
  min-height:200px
}

.square-holder img {
  max-width:100%;
  filter: grayscale(100%);
  transition: all 0.3s;
}

.square-holder:hover img{
  filter:none;
}