<div class="hover-sample">
マウスをあててみて
</div>
.hover-sample{
background-color:red;
width:300px;
text-align:center;
padding:20px;
color:#ffffff;
transition: background-color 0.3s ease-out 0.3s;
}
.hover-sample:hover{
background-color:blue;
}
Also see: Tab Triggers