How to Hide overflow scroller of DIV

I have set a fix height of DIV and set its ove开发者_StackOverflowrflow-y:scroll but the problem is that if i have got data less than its height event though its showing scroll bar (disabled). please tell me how can i hide it... i mean give me solution so that the scrollbar will only show when data in that DIV is crossing height of DIV..

My code :

  <div style="overflow-y:scroll; height:290px">
  a data grid is here
     </div>

---

<div style="overflow-y:auto; height:290px">
  a data grid is here
</div>