  <style>
    .grid > .col {
      background-repeat: no-repeat;
      background-position: center center;
      background-size: 100% auto;
      background-color: #000;
      -webkit-transition: all .125s ease-out;
      transition: all .125s ease-out;
    }
    @media only screen and (min-width: 320px) {
      .grid > .col {
        height: 100px;
        background-size: auto 100%;
      }
    }
    @media only screen and (min-width: 480px) {
      .grid > .col {
        height: 150px;
        backgroun