nav {
  height: 100%;
  position: fixed;
  background: transparent;
  display: flex;
  /*align-items: flex-end;*/
  flex-direction: column;
  justify-content: flex-end;
 }

 nav a.thumb {
  margin: 5px;
  padding: 5px;
  width: 100px;
  height: 100px;
  display: inline-block;
  background-clip: padding-box;
  background-size: cover;
  background-position-y: 20%;
  border: 5px solid rgba(0,0,0,.2);
  outline: 2px solid rgba(255,255,255,.5);
  cursor: pointer;
  color: rgba(255,255,255,0);
  font-family: sans-serif;
  font-size: 12px;
  text-decoration: none;
 }
 nav a:hover.thumb {
  width: 105px;
  height: 105px;
  color: #fff;
  border: 5px solid rgba(0,0,0,.5);
  outline: 2px solid rgba(255,255,255,.75);
 }