.perfectcenter {
  position:absolute;
  top:50%;
  left:50%;
  width:250px;
  height:250px;
  margin-top:-125px; /* half the height */
  margin-left:-125px; /* half the width */
  text-align:center;
}

.roll {
        height: 250px;
        width: 250px;
        margin: 10px;
        float: left;
        border-radius: 100%;
        -webkit-transition: all ease 0.3s;
        -moz-transition: all ease 0.3s;
        -o-transition: all ease 0.3s;
        -ms-transition: all ease 0.3s;
        transition: all ease 0.3s;
}

.roll:hover {
#       background-image: url('/content/keepingitsimple.jpg');
#       box-shadow: 0px 0px 4px 1px rgba(0,0,0,0.8);
        -webkit-transform:rotate(360deg);
        -moz-transform:rotate(360deg);
        -o-transform:rotate(360deg);
        -ms-transform:rotate(360deg);
        transform:rotate(360deg);
}

#clock {
    padding: 10px;
}