Animating max-height to overcome height:auto limitation

by Shidhin C R

HTML

<ul>
    <li class="main">item1
        <ul>
            <li>submenu1</li>
            <li>submenu2</li>
        </ul>
    </li>
    <li class="main">item2
        <ul>
            <li>submenu1</li>
            <li>submenu2</li>
        </ul>
    </li>
    <li class="main">item3
        <ul>
            <li>submenu1</li>
            <li>submenu2</li>
        </ul>
    </li>
    <li class="main">item4
        <ul>
            <li>submenu1</li>
            <li>submenu2</li>
        </ul>
    </li>
</ul>

CSS

ul,li {
    list-style: none;
}
li.main {
 float:left;
 display: block;
 border: 1px solid #000;
 width: 100px;
 background-color: #ccc;
 text-align:center;
    margin: 3px;
    cursor: pointer;
    overflow: hidden;
    font-weight: bold;
}
li.main ul {
    max-height: 0px;
    padding: 0;
    font-weight: normal;
    -moz-transition: 0.5s;
    -ms-transition: 0.5s;
    -o-transition: 0.5s;
    -webkit-transition: 0.5s;
    transition: 1s;
}
li.main:hover ul {
    max-height:999px;
}
li.main ul li {
    margin : 2px;
}
li.main ul li:hover {
    background-color: orange;
    color: white;
}