Template:BouncingDiv/styles.css

.bouncing-container {
  position: relative;
  border: 2px solid #333;
  overflow: hidden;
  margin: 0 auto; /* 居中显示 */
  background-color: #f9f9f9;
}

.bouncing-div {
  position: absolute;
  width: 50px;
  height: 50px;
  background-color: #3498db;
}