CSS中,脚本不能覆盖CSS的!!!

代码如下:

            <style type="text/css">
div#overCamp a
{}{
    color: #00368f;
    text-decoration: none;
    cursor: crosshair
}
.MouseOver
{}{
    color: Red;
    font-weight: bold;
    cursor: pointer;
}
.MouseOut
{}{
    color: Black;
    font-weight: normal;
    color: #00368f;
}
            </style>
            <div id="overCamp" style="POSITION: absolute;  TEXT-ALIGN: center" name="overCamp">
                <a id="human" onmouseover="this.className = 'MouseOver';" onmouseout="this.className='MouseOut' ;">
                    &nbsp;Alliance&nbsp; </a>
                <br>
                <a id="animal" onmouseover="this.className = 'MouseOver';" onmouseout="this.className='MouseOut' ;">
                    &nbsp;Horde&nbsp; </a>
            </div>

这样,在Div#overCamp a 和 .MouseOver 同时出现的属性,不会反映在 .MouseOver 中,即使,事实上也是,脚本控制的类 .MouseOver 在 后面被执行.
把CSS中的Div#overCamp a 改为 div  a ,后者就会覆盖前者.
Why?