.thumbnail-wrap {
  text-align: center;
}

.thumbnail-list {
  width:720px; 
  margin-left:20px; 
  margin-top:15px; 
  height:400px;
  overflow-y: auto;
  overflow-x: hidden;
}

.thumbnail-img {
  width: 180px;
  height: 90px;
  background-color: black;
  border-color: lightskyblue;
  border-style: solid;
  border-width: 1px;
}