body {
  font-family: Arial, sans-serif;
  padding: 20px;
}

.controls {
  margin-bottom: 15px;
}

button {
  padding: 8px 12px;
  margin: 5px;
  cursor: pointer;
}

.bg-change {
  background-color: #211e1e;
}

#playground {
  border: 2px dashed #302121;
  padding: 20px;
  min-height: 120px;
  width: 300px;
}

.box {
  padding: 15px;
  margin: 5px 0;
  width: 100px;
  background-color: rgb(114, 214, 247);
}

.highlight {
  border: 3px solid red;
  background-color: #d09999;
}