Add cellPadding and cellSpacing for radioButton to 0.
<asp:RadioButtonList ID="RadioButtonList2" runat="server" Height="10px" RepeatDirection="Horizontal"
Width="110px" Style="z-index: 1; left: 145px; top: 1px; position: absolute; background-color: InfoBackground;
border-bottom-style: inset;"
Font-Size="X-Small" AutoPostBack="True" CellPadding="0" CellSpacing="0">
hope this helps...