HTML webpart code

<div style="width: 50%; border: solid 2px black;">
            <span>Select the room:</span>
            <asp:DropDownList ID="dd_salas" AutoPostBack="true" runat="server" OnSelectedIndexChanged="dd_salas_SelectedIndexChanged" />
            <br />
            <br />
            <asp:RadioButtonList ID="rbt_graphicType" runat="server" AutoPostBack="true" OnSelectedIndexChanged="rbt_graphicType_SelectedIndexChanged">
                <asp:ListItem Text="Meeting Type" Selected="True" /> <!--Column Chart-->
                <asp:ListItem Text="Meeting Category" /> <!--Pie Chart-->
           </asp:RadioButtonList>
            <asp:Panel ID="pnl_data" runat="server" />
            <!--Div that will hold the pie chart-->
            <div id="chart_div">
            </div>
            <br />
            <asp:Label runat="server" Text="" ID="MessageLabel" />
</div>