Something

   <style type="text/css">
      .hoverOff {
         background-color: #00FF00;
         color:            #000000;
      }
      .hoverOn {
         background-color: #000000;
         color:            #00FF00;
      }
   </style>
   <script type="text/javascript">
      function hoverOff(hoverElement) {
         hoverElement.className = "hoverOff";
      }
      function hoverOn(hoverElement) {
         hoverElement.className = "hoverOn";
      }
   </script>
   <p class="hoverOff">This paragraph has no hover effect.</p>
   <p class="hoverOff" onmouseover="hoverOn(this);" onmouseout="hoverOff(this);">
   This paragraph has a hover effect.</p>