Hi Devender,
First of all, I'd like to say that what you're trying to accomplish with the ShareThis button is very creative! I've yet to see it used like this, but it looks great (in FireFox). :-)
It looks like you're using our Simple API for websites. Might I suggest you use our STAPI?
With the full version, you'll be able to create your own custom ShareThis button and apply whatever CSS/XHTML you wish for the button directly, as well enable your users to share individual blog posts, not just the URL of your website like you have now.
For more information including on how to create your own custom ShareThis button see http://support.sharethis.com/developers