a:link {
color: white;
background-color: black;
text-decoration: none;
border: 2px solid white;
}
a:visited {
color: white;
background-color: black;
text-decoration: none;
border: 2px solid white;
}
a:hover {
color: black;
background-color: white;
text-decoration: none;
border: 2px solid black;
}
Button :
<asp:LinkButton ID="A" runat="server" Text="A" OnClick="searchalpha" cssClass="a"></asp:LinkButton>  
it's not working do you any solution for this...thank you