Hide TextBox Border in IE 7

hi

i have TB in my page and this is my TB css

 .txtsearch
   {
        
        width:285px;
        height:20px;
        direction:rtl;
         font-size:18px;
         font-weight:bold;
         border-style:none;
       }

i put  border-style:none; but in IE7 it showed my TB border?what can i do?