div.polaroid{
    width: 24%;
    background-color: whitesmoke;
    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
}

img{
    width: 100%;
    height: auto;
}

div.container{
    text-align: center;
    padding: 10px 20px;
}

.responsive {
    margin: 0 6px;
    float: left;
    width: 24%;
}

@media only screen and (max-width: 700px){
  .responsive {
    width: 49.99999%;
    margin: 6px 0;
  }
}

@media only screen and (max-width: 500px){
  .responsive {
    width: 100%;
  }
}

ul.stacks{
    list-style-type: none;
    display: inline-block;
}