<div class="dropdown"><!-- The trigger element --><button>...</button><!-- The content --><div class="dropdown__content">...</div></div>
.dropdown {position: relative;}/* Hide the dropdown's content by default */.dropdown__content {display: none;/* Position it right below the trigger element */left: 0;padding-top: 4px;position: absolute;top: 100%;/* It should be on the top of other elements */background-color: #fff;z-index: 9999;/* Size */height: 200px;width: 200px;}/* Show the content when hover on the container */.dropdown:hover .dropdown__content {display: block;}