.custom-topic-dropdown{display:inline-block;position:relative}.dropdown-menu{background-color:#fff;box-shadow:0 4px 8px rgba(0,0,0,.15);display:none;max-height:300px;min-width:220px;overflow-y:auto;position:absolute;z-index:10}.dropdown-menu.open{display:block}.dropdown-menu h4{border-bottom:1px solid #ddd;font-size:16px;margin:0;padding:10px 15px}.dropdown-menu ul{list-style:none;margin:0;padding:0}.dropdown-menu li a{color:#333;display:block;padding:10px 15px;text-decoration:none}.dropdown-menu li a:hover{background-color:#f5f5f5}