.thumb {
  width: 280px;
  height: 280px;
  float: left;
  position: relative;
  cursor: pointer;
  display: table; }
  .thumb .center {
    display: table-cell;
    vertical-align: middle; }
  .thumb img {
    display: block;
    margin-right: auto;
    margin-left: auto;
    border: 2px solid white; }

.thumb.over img {
  border-color: #686161; }