.menu{list-style:none;padding:0;width:200px;}.menu >li{margin:0;padding:0;}.menu-title{cursor:pointer;background-color:#f0f0f0;padding:10px;border-bottom:1px solid #ddd;transition:background-color 0.3s;}.menu-title:hover{background-color:#e0e0e0;}.sub-menu {list-style:none;margin:0;padding:0;max-height:0;overflow:hidden;transition:max-height 0.3s ease-in-out;}.sub-menu li{cursor:pointer;transition:background-color 0.3s;}.sub-menu li:hover{background-color:#e0e0e0;}.menu.active .sub-menu{max-height:1000px;}