body {
  background: #222;
  margin-top: 20px;
  font-family: Arial, Helvetica, sans-serif;
  color: white;
}
.thumbnails img {
  height: 80px;
  border: 4px solid #555;
  padding: 3px;
  margin: 0 10px 10px 0;
}
.thumbnails img:hover {
  border: 4px solid #0000ff;
}

.preview {
  padding: 3px;
  width: 400px;
}
.preview img {
  width: 400px;
  height: 400px;
}