Use max-height
in the transition and not height
. And set a value on max-height
to something bigger than your box will ever get.
See JSFiddle demo provided by Chris Jordan in another answer here.
#menu #list { max-height: 0; transition: max-height 0.15s ease-out; overflow: hidden; background: #d5d5d5; } #menu:hover #list { max-height: 500px; transition: max-height 0.25s ease-in; }
<div id="menu"> <a>hover me</a> <ul id="list"> <!-- Create a bunch, or not a bunch, of li's to see the timing. --> <li>item</li> <li>item</li> <li>item</li> <li>item</li> <li>item</li> </ul> </div>