Change CSSclass of panel

Question

I am trying to dynamically change CSS class of panel in code behind.

I tried with DIV with runat="server" and div.Attributes["class"]="myClass". No success.

Then I went with asp panel. myPanel.cssClass = "myClass" ... no success.

I also tried AnthonyWJones's solution here: Best way to change CSS Classes from code With:

myPanel.RemoveCssClass("arrow_box");
myPanel.AddCssClass("arrow_boxMS");

Still no success.

The only thing I would like to change is arrow of the div. I helped myself with this (to generate CSS): http://cssarrowplease.com/

My CSS:

.arrow_box, .arrow_boxMS
{
    position: relative; /*background: #88b7d5;*/
    border: 2px solid #c2e1f5;
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    border-radius: 5px;
    margin-top: 15px;
    z-index: -1;
}
.arrow_box:after, .arrow_box:before
{
    bottom: 100%;
    border: solid transparent;
    content: " ";
    height: 0;
    width: 0;
    position: absolute; /*pointer-events: none;*/
}
.arrow_box:after
{
    border-color: rgba(136, 183, 213, 0);
    border-bottom-color: #ffffff; /*#88b7d5;*/
    border-width: 15px; /*SET height of smaller triangle within arrow. IMPORTANT bigger triangle is set in .arrow_box:before class*/
    left: 8%;
    margin-left: -15px;
}
.arrow_box:before
{
    border-color: rgba(194, 225, 245, 0);
    border-bottom-color: #c2e1f5;
    border-width: 18px; /* SET height of bigger triangle - arrow IMPORTANT: difference between triangles must reflect how many pixels is border*/
    left: 8%;
    margin-left: -18px; /*if border thickness is changed adjust this to fit triangles*/
}

.arrow_boxMS:after, .arrow_boxMS:before
{
    bottom: 100%;
    border: solid transparent;
    content: " ";
    height: 0;
    width: 0;
    position: absolute; /*pointer-events: none;*/
}
.arrow_boxMS:after
{
    border-color: rgba(136, 183, 213, 0);
    border-bottom-color: #ffffff; /*#88b7d5;*/
    border-width: 15px; /*SET height of smaller triangle within arrow. IMPORTANT bigger triangle is set in .arrow_box:before class*/
    left: 25%;
    margin-left: -15px;
}
.arrow_boxMS:before
{
    border-color: rgba(194, 225, 245, 0);
    border-bottom-color: #c2e1f5;
    border-width: 18px; /* SET height of bigger triangle - arrow IMPORTANT: difference between trinagles must reflect how many pixels is border*/
    left: 25%;
    margin-left: -18px; /*if border thickness is changed adjust this to fit triangles*/
}

The triangle just wouldn't change when button is clicked.

Any ideas?

EDIT:

<asp:UpdatePanel runat="server">
                <ContentTemplate>
                    <table id="tblSelection">
                        <tr>
                            <td>
                                <asp:Button ID="btn1" Text="1" CssClass="button" ClientIDMode="Static"
                                    runat="server" OnClick="btn1_Click" />
                            </td>
                            <td>
                                <asp:Button ID="btn2" Text="2" CssClass="button" ClientIDMode="Static"
                                    runat="server" OnClick="btn2_Click" />
                            </td>
                            <td>
                                <asp:Button ID="btn3" Text="3" CssClass="button" runat="server" OnClick="btn3_Click" />
                            </td>
                            <td>
                                <asp:Button ID="btn4" Text="4" CssClass="button" runat="server"
                                    OnClick="btn4_Click" />
                            </td>
                            <td>
                                <asp:Button ID="btn5" Text="5" CssClass="button" runat="server"
                                    OnClick="btn5_Click" />
                            </td>
                            <td>
                                <asp:Button ID="btn5" Text="5" CssClass="button" runat="server" OnClick="btn5_Click" />
                            </td>
                        </tr>
                    </table>
                </ContentTemplate>
            </asp:UpdatePanel>

            <asp:Panel id="divDaySelection" runat="server">           
                        <table id="tblDaySelection">
                            <tr>
                                <td>
                                    <asp:CheckBox ID="cbAllDays" Text="All" runat="server" 
                                        oncheckedchanged="cbAllDays_CheckedChanged" AutoPostBack="true" />
                                </td>
                                <td>
                                    <asp:CheckBox ID="cbMon" Text="Monday" runat="server" />
                                </td>
                                <td>
                                    <asp:CheckBox ID="cbTue" Text="Tuesday" runat="server" />
                                </td>
                                <td>
                                    <asp:CheckBox ID="cbWed" Text="Wednesday" runat="server" />
                                </td>
                                <td>
                                    <asp:CheckBox ID="cbThu" Text="Thursday" runat="server" />
                                </td>
                                <td>
                                    <asp:CheckBox ID="cbFri" Text="Friday" runat="server" />
                                </td>
                                <td>
                                    <asp:CheckBox ID="cbSat" Text="Saturday" runat="server" />
                                </td>
                                <td>
                                    <asp:CheckBox ID="cbSun" Text="Sunday" runat="server" />
                                </td>
                            </tr>
                        </table>

            </asp:Panel>

Seems like updatepanel was problem since I am getting results right now ... now that I removed it.

Answer 1

As I (during editing post) and rocky figured it out the problem was that the panel was not in the updatepanel.

Technically all of my methods of changing CSS would work.

Answer 2

The problem is that the panel is not in the updatepanel...