body {
  background-color: black;
}
#grid {
  margin:10px auto;
  display:grid;
  width:960px;
  height:720px;
  grid-template-rows: repeat(5,144px);
  grid-template-columns: repeat(6,160px);
}    
.piece {
  grid-row: 1/ span 1;
  grid-column: 1/ span 1;
  width:100%;
  height:100%;
  outline:1px solid red;
  outline-offset:-1px;
}
.highlight {
  outline:5px solid lightgreen;
  outline-offset:-5px;
}
#pic {
  grid-row: 1/ span 5;
  grid-column: 1/ span 6;
  visibility: hidden;
}