https://www.lejiancc.com/lyear_components_dropdowns.html
<div class="btn-group dropup"> <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false"> 十一月的萧邦 </button> <ul class="dropdown-menu"> <li><a class="dropdown-item" href="#">四面楚歌</a></li> <li><a class="dropdown-item" href="#">夜曲</a></li> <li><a class="dropdown-item" href="#">一路向北</a></li> <li><hr class="dropdown-divider"></li> <li><a class="dropdown-item" href="#">珊瑚海</a></li> </ul> </div> <div class="btn-group dropup"> <button type="button" class="btn btn-secondary"> 十二新作 </button> <button type="button" class="btn btn-secondary dropdown-toggle dropdown-toggle-split" data-bs-toggle="dropdown" aria-expanded="false"> <span class="visually-hidden">切换下拉</span> </button> <ul class="dropdown-menu"> <li><a class="dropdown-item" href="#">四季列车</a></li> <li><a class="dropdown-item" href="#">乌克丽丽</a></li> <li><a class="dropdown-item" href="#">比较大的大提琴</a></li> <li><hr class="dropdown-divider"></li> <li><a class="dropdown-item" href="#">傻笑</a></li> </ul> </div>
