Highlighting Current Page in ASP.NET Master Page

Question

 If i write my menu like

<li><a runat="server" href="#nogo1" <span>Home</span></a></li>   

then highlighting current page works

but if i write my menu like  

 <li><a runat="server" href="~/Default" <span>Home</span></a></li>

then highlighting stops working but this is the way i want

 

Can someone pliz help 

 

I have this JQUERY

 

 $(document).ready(function () {

            $('.topmenu a').click(function () {

                $(".topmenu a").removeClass("item_active");

                $(this).addClass('item_active');

            });

        });</script>

 

My Css like this

 

.topmenu {

height:37px;

border:0;

margin:0;

}

.topmenu ul,.topmenu ul li {

list-style:none;

float:left;

margin:0;

padding:0;

}

.topmenu ul {

float:right;

margin:57px 0 0;

}

.topmenu ul li a {

background:url(images/right_798a701.png) right top no-repeat;

text-decoration:none;

display:block;

float:left;

border:0;

margin:0 5px 0 0;

padding:0;

}

.topmenu ul li a span {

display:block;

background:url(images/left_798a701.png) left top no-repeat;

font-family:"Lucida Sans Unicode", Verdana, Arial, Helvetica, sans-serif;

font-size:13px;

color:#fff;

line-height:40px;

font-weight:400;

font-style:normal;

text-decoration:none;

padding:0 15px;

}

.topmenu ul li a:hover,.topmenu ul li a.item_active {

background:#FF0000; 

}

.topmenu ul li a:hover span,.topmenu ul li a.item_active span {

background:#FF0000; 

font-weight:400;

font-style:normal;

text-decoration:none;

}