CSS里也写脚本

<style type="text/css">
.showCSS
{
    event:expression(
    onmouseover = function()
    {
        this.style.backgroundColor='#ff0000'
    },
    onmouseout = function()
    {
        this.style.backgroundColor='#ffffff'
    }
    )
}
</style>

<div class="showCSS">把鼠标放上去试试看！</div>