body {
  font-family: Arial, sans-serif;
  margin: 20px;
  background: #f7f7f7;
}

h1, h2 {
  color: #333;
}

input {
  padding: 5px;
  margin-right: 5px;
}

button {
  padding: 5px 10px;
  margin: 5px 5px 5px 0;
  cursor: pointer;
}

#linked-list, #queue {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  margin-top: 10px;
}

.node, .queue-node, .tree-node {
  padding: 10px;
  margin: 5px;
  background-color: #d1e7dd;
  border: 2px solid #0f5132;
  border-radius: 6px;
  font-weight: bold;
  animation: pop 0.3s ease-in-out;
}

.arrow {
  margin: 0 5px;
}

#binary-tree {
  margin-top: 20px;
}

@keyframes pop {
  0% { transform: scale(0.5); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}