<style type="text/css">
.showCSS{
event:expression(
onmouseover = function()
{
this.style.backgroundColor='#f0f0f0'
},
onmouseout = function()
{
this.style.backgroundColor='#ffffff'
}
)
}
</style>
<div class="showCSS">把鼠标放上去试试看！：）</div>