📅  最后修改于: 2022-03-11 15:02:26.880000             🧑  作者: Mango
#wrapper {
background: #ccc;
overflow: hidden;
transition: max-height 300ms;
max-height: 0; /* <---hide by default */
}
#wrapper.open {
max-height: 100px; /* <---when open, allow content to expand to take up as much height as it needs, up to e.g. 100px */
}