php 切换背景色彩或背景图片或是切换模板是怎样实现的

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<TR style="FONT-WEIGHT: bold; FONT-STYLE: normal; BACKGROUND-COLOR: white; TEXT-DECORATION: none"    onMouseOver="this.style.backgroundColor='yellow'"onMouseOut="this.style.backgroundColor='white'"><br />

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<style><br />
.tr1{ font-weight: bold; font-style:normal; background-color: white; text-decoration:none; }<br />
.over{ background:yellow}<br />
</style><br />

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<script src="../js/jquery-1.5.1.min.js" type="text/javascript"></script> //记得包含jQuery插件文件<br />
<script type="text/javascript"><br />
$(function(){<br />
    $(".tr1").bind("mouseover mouseout",function(){<br />
	     $(this).toggleClass("over");<br />
	});<br />
});<br />
</script><br />

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<TR class="tr1"><TD width="10%">姓名</TD></TR><br />
<TR class="tr1"><TD width="10%">密码</TD></TR><br />
<TR class="tr1"><TD width="10%">姓名</TD></TR><br />
<TR class="tr1"><TD width="10%">密码</TD></TR><br />