[рони]

iosweb,

<style type="text/css">
    body{
      background-color: #D3D3D3;
    }

  </style>
<ul>
  <li><a  onclick="return black(this)" href="">Новости</a></li>
  <li><a  onclick="return black(this)" href="">Новости</a></li>
  <li><a  onclick="return black(this)" href="">Новости</a></li>
</ul>
<script>
var black = function() {
    var temp;
    return function(Element) {
        temp && (temp.style.borderBottom = "");
        temp = Element;
        temp.style.borderBottom = "4px solid white";
        return false
    }
}();
</script>