css - webkit border radius question -

here's problem: i'm showing overlay (using this) message div has rounded corners.

here css code message div:

#modal1 {     margin-left: auto;     margin-right: auto;     display: none;     width: 620px;     height: 150px;     position: relative;     background-color: #fff;      border: 12px solid #ff771c;       -webkit-border-top-left-radius: 12px;     -webkit-border-top-right-radius: 12px;     -webkit-border-bottom-left-radius: 12px;     -webkit-border-bottom-right-radius: 12px;      text-align: center; } 

and problem white "border" (if closely) in upper left , right corners. here image can see yourself. now, "solved" putting top-left , -right border properties of webkit 0px, not solution, i'm asking if have maybe ideas? btw, developed chrome that's why it's -webkit there in code..

edit:
found solution on forum http://flowplayer.org/tools/forum/40/46850

this seems border of div or element behind rounded bordered div