body {
  font-family: sans-serif;
  text-align: center;
  padding: 40px;
}

.stage {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 40px;
  margin-bottom: 30px;
}

/* shared */
.shape {
  transition: transform 0.4s ease;
}

/* square */
.square {
  width: 80px;
  height: 80px;
  background: #4caf50;
}

.square.grow {
  transform: scale(1.6);
}

/* circle */
.circle {
  width: 80px;
  height: 80px;
  background: #2196f3;
  border-radius: 50%;
}

.circle.pulse {
  animation: pulse 1s ease-in-out infinite;
}

@keyframes pulse {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.4);
  }
  100% {
    transform: scale(1);
  }
}

/* triangle */
.triangle {
  width: 0;
  height: 0;
  border-left: 40px solid transparent;
  border-right: 40px solid transparent;
  border-bottom: 70px solid #ff5722;
  transition: transform 0.3s ease;
}

.triangle:hover {
  transform: scale(1.5);
}

button {
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
}