/* v-if/v-show 都可用，整段滑出/收合 */
.collapse-enter-active,
.collapse-leave-active {
    overflow: hidden;
    transition: max-height .25s ease, opacity .2s ease;
}

.collapse-enter-from,
.collapse-leave-to {
    max-height: 0;
    opacity: 0;
}

.collapse-enter-to,
.collapse-leave-from {
    max-height: 600px; /* 依頁面內容調整到足夠大 */
    opacity: 1;
}

/* 供 JS 版本 B 使用 */
.collapse-transition {
    transition: height .25s ease;
    overflow: hidden;
}