Add Media Screen CSS to Bootstrap element using CSS

 <asp:Panel ID="pnlBen" runat="server">
        <div class="row">
            <%--<div class="col-md-2"></div>--%>
            <div class="col-md-12">
                
              
                      <asp:Image runat="server" ImageUrl="~/images/benefits/19.18.17-bottom%20banner%20-%20Build.jpg" ID="imgInterestedIN" CssClass="img-responsive" />   
                       <div  id="dvtwoevent" style="padding-top:13px;padding-left:32px;background-color:#eaeaea;padding-bottom:5px;">
                            <table>
                                  <tr><td valign="top" > <asp:RadioButtonList ID="rdoInterested" Font-Size="13px"  CssClass="rdobuttn"  
                                       runat="server" AutoPostBack="True"             
                                   RepeatDirection="Horizontal">
                                   <asp:ListItem>Yes,I am Interested in Both Events. Please Send me More Information</asp:ListItem>
                                   <asp:ListItem >Sorry , Not Interested</asp:ListItem>  
                                   </asp:RadioButtonList></td><td style="padding-left:45px;"><asp:Button ID="buttnSend" runat="server" CssClass="dvSend" ToolTip="Please Select Option" ForeColor="White" BackColor="#fd0200" Text="Send" Width="70px"
                                   Enabled="False" /></td></tr>

                            </table>
                            </div>
                
            </div>
          <%--  <div class="col-md-2"></div>--%>
        </div>
             </asp:Panel>

 i wanted to apply css for 

<div class="col-md-12">

how to apply?

@media screen and (max-width: 480px) {
.row .col-md-12{
}
}

Is it like this?