Change title css and area radius size in ImageMap of MS Chart

Question

How to change title element css of area element of imagemap which is there in MS Chart.

For i.e.

<map id="ctl00_ContentPlaceHolder1_chtActivityImageMap" name="ctl00_ContentPlaceHolder1_chtActivityImageMap">
      <area alt="" title="30-07-2013 : 600" coords="618,180,623,185" shape="rect" style="cursor:pointer">
      <area alt="" title="29-07-2013 : 400" coords="609,207,614,212" shape="rect" style="cursor:pointer">
      <area alt="" title="30-05-2013 : 1400" coords="80,70,85,75" shape="rect" style="cursor:pointer">
</map>

Here, it is the code of MS chart area. I want to change css of title element. And I also want to increase radius of area element when anyone hover on it.