.jumbotron{
    cursor: pointer;
    width: 10rem; /* 设置宽度为300px */
    height: 10rem; /* 设置高度为300px，与宽度相等，确保为正方形 */
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0; /* 取消默认的内边距 */
}