ajaxcontorltoolkit modal popup showing behind div position fixed - asp.net

Question

I have a header div on top of the page with Position: fixed in the master page.
In the content page, I have a modal Popup, that I would like to consume most of the screen, but the popup shows from the point where the header div ends (i.e., from the top)
I have this css for the popup and popup background classes...
.modalBackground {
background-color: #AAAAAA;
-moz-opacity: 0.7;
opacity: 0.7;
filter: alpha(opacity=70);
}
.modalPopup {
position: relative;
min-height: 200px;
width: 100%;
border: solid 1px #e5e5e5;
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
background-color: #f5f6f5;
}
and this css is generated (after the modal popup is shown) for modal background:
{
position: fixed;
left: 0px;
top: 0px;
z-index: 10000;
width: 1003px;
height: 598px;
}
UPDATE 1
Here is the ModalPopup markup:
<ajaxToolkit:ModalPopupExtender ID="mpeImageViewer" runat="server" Drag="false" PopupControlID="pnlImageViewer" Y="90"
TargetControlID="imgEmpty" BackgroundCssClass="modalBackground" CancelControlID="imgClose" DropShadow="true">
</ajaxToolkit:ModalPopupExtender>
and the Panel markup:
<asp:Panel ID="pnlImageViewer" runat="server" Style="display: none;" Width="975px" Height="550px" CssClass="modalPopup"></asp:Panel>
UPDATE 2
There is a menu in the Header, which also needs to be displayed. I am thankful to all the efforts made by people specially by __.
I am going to share a screenshot of the popup in a few minutes
UPDATE 3
Attaching source code after Viewing source code from Chrome...
Source Code
UPDATE 4
Attaching the corresponding CSS files...
Menu.css
Default.css

Answer 1

When you have the following HTML structure:
<div class="header">
here is your header content
</div>
<div class="content">
here is your model somewhere
</div>
And your .header has an z-index:2; and your .content has an z-index:1; the content inside this division (and maybe in this case your model) will always appear below your header.
I cannot think of anything else in this case.

Answer 2

For future questions, I highly recommend posting the generated HTML client code as well since that is what the CSS is acting upon. It will help people understand the problem faster and find a solution faster.
Without seeing your full source or client HTML, this is all speculation; however, I believe your issue is related to the stack(ing) order.
Basically, what I imagine your setup to be (especially judging by your response to Rens Tillmann's answer) is the following:
HTML:
<div id="header">
...Fixed content showing above modal popup...
</div>
<div id="content">
...Modal background element + Modal popup content...
</div>
In this case, if #header has a z-index greater than that of #content's z-index (assuming #content has proper stacking context), then the fixed header will always show up above the modal content because the modal content is in a subcontext of #content's stacking context. This means that no matter what z-index you give the modal content, it will always be below #header.
Here is a JSFiddle to illustrate the issue.
So, what can we do? There are four solutions to get the modal content above #header that I can think of at the moment.
Solution 4 is the easiest potential solution if your website design allows it.
Solution 1:
Make #content have a higher stacking order than #header. This is not the answer, because I am assuming we need #header to float above #content.
Doing it this way will have the normal content show up above the header content.
JSFiddle to illustrate why this won't work.
Solution 2:
Put #header into the same stacking context as the modal. This can work; however, depending upon how your webpage is laid out in HTML and CSS, this may not be possible.
To put #header into the same stacking context as the modal, the easiest way would be to move it to be a sibling element of the modal.
JSFiddle to illustrate this solution.
Another potential drawback of this solution is that it may be semantically confusing to have your header inside your content.
Solution 3:
Put the modal background + content into the same stacking context of the #header element. Depending upon how your ASP.Net code is set up, this may not be possible. I don't fully grasp how AjaxControlToolkit works; so I don't know if this is possible or not.
The easiest way to do this would be to move the ModalPopup and Panel markups to be siblings of the #header element.
HTML:
<ajaxToolkit:ModalPopupExtender ID="mpeImageViewer" runat="server" Drag="false" PopupControlID="pnlImageViewer" Y="90"
TargetControlID="imgEmpty" BackgroundCssClass="modalBackground" CancelControlID="imgClose" DropShadow="true">
</ajaxToolkit:ModalPopupExtender>
<asp:Panel ID="pnlImageViewer" runat="server" Style="display: none;" Width="975px" Height="550px" CssClass="modalPopup"></asp:Panel>
<div id="header">
...fixed header content...
</div>
<div id="content">
...regular content...
</div>
If you do this, their z-index values will be in the same context and can affect each other.
Here is a JSFiddle to illustrate this in action.
Note 1:
In Solution 3, you can also put the modal in a stacking context higher than #header's stacking context and it will still work.
For example, this would also work (assuming the modal has a higher z-index than the #wrapper element):
<ajaxToolkit:ModalPopupExtender ID="mpeImageViewer" runat="server" Drag="false" PopupControlID="pnlImageViewer" Y="90"
TargetControlID="imgEmpty" BackgroundCssClass="modalBackground" CancelControlID="imgClose" DropShadow="true">
</ajaxToolkit:ModalPopupExtender>
<asp:Panel ID="pnlImageViewer" runat="server" Style="display: none;" Width="975px" Height="550px" CssClass="modalPopup"></asp:Panel>
<div id="wrapper">
<div id="header">
...fixed header content...
</div>
<div id="content">
...regular content...
</div>
</div>
Note 2:
To be in the same stacking context, you do not have to be sibling elements. You should have sibling stacking contexts though.
For example:
<div class="has-stacking-context" style="z-index: 2;">
(stacking context sibling 1)
...content will show in middle...
</div>
<div class="no-stacking-context">
<div class="no-stacking-context">
<div class="has-stacking-context" style="z-index: 3;">
(stacking context sibling 2)
...content will show above everything...
</div>
</div>
</div>
<div class="has-stacking-context" style="z-index: 1;">
(stacking context sibling 3)
<div class="no-stacking-context">
<div class="has-stacking-context" style="z-index: 100000;">
(subcontext of sibling 3's stacking context)
...content will show below everything...
</div>
</div>
</div>
Moving elements physically (as I've done in Solution 2 and 3) just side-steps any need to remove various stacking contexts to get two stacking contexts to be siblings. Sometimes it is not possible to remove the stacking context of some elements.
Solution 4 (can it be this simple?):
This is basically another way of doing Solution 3. Instead of physically moving the modal elements to match up the stacking contexts, we eliminate stacking contexts blocking the #header and modal element stacking contexts from being siblings.
Depending upon how your CSS is set up, this may or may not work.
For example, it may be possible to just remove the #content element's stacking context so that they become stacking context siblings.
Here is a JSFiddle to illustrate the easiest potential solution.
Notice that I removed the z-index property (and position property) of the #content element. It now has no stacking context. You can do this to all ancestor elements of the modal elements to see if it works. Keep in mind though that some of those ancestors may actually need their stacking contexts...
Final Solution (after chatting with you):
So, after looking at your code. I basically solved the issue using Solution 4. Your structure looks like the following:
<div class="HeaderContainer">
</div>
<div id="contentAreaMasterPage">
<div id="ctl00_MainContentPlaceHolder_ImageThumbnailList_ImageViewer_mpeImageViewer_foregroundElement" style="position: fixed; z-index: 100001; left: 38.5px; top: 10px;">...</div>
<div id="ctl00_MainContentPlaceHolder_ImageThumbnailList_ImageViewer_mpeImageViewer_backgroundElement" class="modalBackground" style="position: fixed; left: 0px; top: 0px; z-index: 10000; width: 1003px; height: 601px;"></div>
</div>
Because .HeaderContainer has a z-index of 10 and #contentAreaMasterPage has a z-index of 9, everything inside #contentAreaMasterPage will always show up below .HeaderContainer1. So even though the two modal elements have z-index values more than 100 times that of .HeaderContainer's z-index of 10, they will always show up below it because they're inside #contentAreaMasterPage's z-index of 9.
Thus we want to get rid of #contentAreaMasterPage's z-index so that it no longer has a stacking context to get in-between .HeaderContainer's and the modal elements' z-index values. It's safe to remove the z-index in this case because .HeaderContainer will show up above #contentAreaMasterPage anyway without #contentAreaMasterPage needing a lower z-index.
The related solution CSS code is thus simply:
#contentAreaMasterPage {
z-index: auto !important;
}
Which goes inside your specific page since you cannot modify the master template nor the master CSS file.

Answer 3

try with position: relative; instead of position: fixed;
.modalPopup {
position: absolute;
min-height: 200px;
width: 100%;
border: solid 1px #e5e5e5;
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
background-color: #f5f6f5;
}
{
position: relative;
left: 0px;
top: 0px;
z-index: 10000;
width: 1003px;
height: 598px;
}
for example
<tr>
<td colspan="2">
<asp:Button ID="btnSurveyId" runat="server" Style="display: none;" />
<cc1:ModalPopupExtender ID="mpeSurveyId" runat="server" TargetControlID="btnSurveyId"
CancelControlID="imgCloseSurveyId" BackgroundCssClass="modalBackground" PopupControlID="pnlSurveyId"
PopupDragHandleControlID="pnlIdSurveyName" Drag="true" DropShadow="true">
</cc1:ModalPopupExtender>
<asp:Panel ID="pnlSurveyId" runat="server" CssClass="modalBox" Width="250px" Height="100px"
Style="display: none;">
<asp:Panel ID="pnlIdSurveyName" runat="server" CssClass="caption" Style="margin-bottom: 10px;
cursor: move;">
<table border="0" cellpadding="0" cellspacing="0" style="width: 100%">
<tr style="border: solid 1px balck; background-color: Gray;">
<td>
<strong style="color: White; vertical-align: middle;"><span id="Span2" runat="server">
Change Survey Id</span></strong>
</td>
<td align="right" valign="top" style="cursor: pointer;">
<img id="imgCloseSurveyId" alt="Close" src="../Images/close.gif" />
</td>
</tr>
</table>
</asp:Panel>
<div style="width: 100%">
<table>
<tr>
<td>
<asp:DropDownList ID="ddlSurveyName" runat="server" Width="190px" Style="margin-left: 30px;">
</asp:DropDownList>
</td>
</tr>
<tr>
<td style="padding: 5px;">
<asp:Button ID="btnSubmitSurvey" runat="server" Text="Submit" Width="100px" ValidationGroup="SurveyId"
Style="margin-left: 20px;" OnClick="btnSubmitSurvey_Click" />
<asp:Button ID="btnCancelSurvey" runat="server" CausesValidation="False" Text="Cancel"
Width="90px" OnClick="btnCancelSurvey_Click" Style="margin-left: 5px;" />
</td>
</tr>
</table>
</div>
</asp:Panel>
</td>
</tr>

Answer 4

In your markup:
<ajaxToolkit:ModalPopupExtender ... PopupControlID="pnlImageViewer" Y="90" ...
you have specified Y="90", this will cause the popup to display 90 pixels off the top. Please try after removing this.

Answer 5

apply zindex to the model popup div greater than that of background div
e.g.
.modalPopup {
position: absolute;
min-height: 200px;
width: 100%;
border: solid 1px #e5e5e5;
-moz-border-radius: 8px;
-webkit-border-radius: 8px;
border-radius: 8px;
background-color: #f5f6f5;
z-index: 90000;
}

Answer 6

Try the following(worked for me):
This is the background style for the modal popup
.modalBackground
{
background-color:#414141;
filter:alpha(opacity=70);
opacity:0.7;
position:absolute;
}
Following is the style for the panel which you want to display
.Panel_Popup_Style
{
background-color:White;
}