我的還是可以的，請看下面

<div id="nav2">
? ?<input type="radio" name="radio-set" id="r1" checked="checked">
? ?<a href="#html5">HTML5</a>
? ?<input type="radio" name="radio-set" id="r2">
? ?<a href="#css3">CSS3</a>
? ?<input type="radio" name="radio-set" id="r3">
? ?<a href="#js">JavaScript</a>
? ?<input type="radio" name="radio-set" id="r4">
? ?<a href="#jquery">Jquery</a>
? ?<input type="radio" name="radio-set" id="r5">
? ?<a href="#ajax">Ajax</a>
</div>

#nav2 input:checked+a,#nav2 input:checked:hover+a{
? ?background: burlywood; ? ?/*被選中的單選按鈕后面的a顏色加深*/
}
#nav2 input:checked + a:after{ ? ?/*為導航添加三角*/
? ?content: "";
? ?width: 0px;
? ?height: 0px;
? ?overflow: hidden;
? ?border-top:20px solid burlywood;
? ?border-left:20px solid transparent;
? ?border-right:20px solid transparent;
? ?position: absolute;
? ?top: 90%;
? ?left: 40%;
}
#nav2 input:hover + a{
? ?background-color: navajowhite; ? ? /*鼠標滑過變色*/
}