body {
  font-family: sans-serif;
  margin: 0;
  padding: 0;
}
#controls {
  padding: 10px;
  background: #ddd;
}
#controls input, #controls button, #controls select {
  margin-right: 10px;
}
#container {
  display: flex;
  height: 90vh;
}
#sidebar {
  width: 200px;
  overflow-y: scroll;
  border-right: 1px solid #ccc;
  padding: 10px;
  background: #f5f5f5;
}
#sidebar img.thumbnail {
  width: 100%;
  margin-bottom: 10px;
  cursor: pointer;
}
#grid {
  flex: 1;
  display: grid;
  gap: 2px;
  padding: 10px;
  background: #eee;
}
.cell {
  background: white;
  border: 1px dashed #ccc;
  position: relative;
  width: 300px;
  height: 300px;
}
.cell img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}