圆角按钮ASP.NET

<asp:LinkButton ID="lbtnSignIn" class="button" runat="server" OnClick="lbtnSignIn_Click"><span>Sign In</span></asp:LinkButton>

.button
{   
    background: transparent url('../../Images/ButtonLeft.gif') no-repeat top left;  
    display: block;
    float: left;
    line-height: 11px; /* 21px (Button Background) = 5px (padding-top) + 11px (font-size) + 5px(padding-bottom) */
    height: 21px; /* Button Background Height */
    padding-left: 9px;  
    text-decoration: none;
    font-weight: bold;
    color: white;
    font-size: 11px;    
}

a:link.button,a:visited.button,a:active.button
{
    color: white;
    text-decoration: none;
    margin-right: 10px;
}

a.button:hover
{ 
    background-position: bottom left;
}

a.button span,a.button span 
{
    background: transparent url('../../Images/ButtonRight.gif') no-repeat top right;    
    display: block;
    padding: 5px 9px 5px 0; /*Set 9px below to match value of 'padding-left' value above*/
}

a.button:hover span
{ 
    background-position: bottom right;
    color: white;
}