CSS3 Transitions: Fade In Element

Useful UI enhancement for making links etc. fade in on mouseover.

HTML

<div id="hover">Hover</div>
<ul>
<li>menu</li>
<li>menu</li>
<li>menu</li>
<li>menu</li>
<li>menu</li>
<li>menu</li>
</ul>
<div id="stuff">stuff</div>

CSS

#stuff {
    opacity: 0.0;
    -webkit-transition: all 500ms ease-in-out;
    -moz-transition: all 500ms ease-in-out;
    -ms-transition: all 500ms ease-in-out;
    -o-transition: all 500ms ease-in-out;
    transition: all 500ms ease-in-out;
}
#hover {
    width:80px;
    height:20px;
    background-color:green;
    margin-bottom:15px;
}
#hover:hover + #stuff {
    opacity: 1.0;
}