Позиционирование календаря в ASP.NET

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Я новичок в разработке веб-страниц.

У меня есть 9 кнопок изображения на веб-странице. При нажатии на каждую кнопку изображения отображается календарь, но когда календарь виден , все содержимое страницы опускается, а когда не видно, все содержимое появляется
Как это исправить?

Я тоже пробовал z-индекс, но безуспешно

Мой код выглядит следующим образом:

Что я уже пробовал:

<%@ Page Language="C#" MasterPageFile="~/Site1.Master" AutoEventWireup="true" CodeBehind="create_projects.aspx.cs" Inherits="OtomasyonSite.projecttracker.createprojects.create_projects" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
        
        .auto-style9 {
            margin-top: 10px;
            text-align: justify;
            font-size: x-large;

            


        }
        

    



  
 <asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
     <asp:Panel ID="Panel1" CssClass="cst" runat="server">
         <div>
     <asp:Label ID="lbl_PageInfo" runat="server" Style="color: #1c3564;" Font-Bold="True"  Font-Size="X-Large" ForeColor="#333333" Text="Create Projects" >
             </div>
    

     <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
     
    <asp:Panel ID="pnl_create"  Style="max-height: 920px;" runat="server" ScrollBars="Vertical" BorderStyle="Outset" Direction="LeftToRight" >
      
        <p>
            
        <asp:Label ID="lbl_projtype" runat="server" Text="Project Type" Width ="150px">
            <asp:DropDownList ID="ddlist_projtype" CssClass="dropdownlist" Style="width: 191px;" runat="server"  AutoPostBack="True">
                        <asp:ListItem Selected="True" Value="Select.." Text="Select..">
                        <asp:ListItem Value="A" Text="A">
                        <asp:ListItem Value="B" Text="B">
                        <asp:ListItem Value="C" Text="C">
            
                

            
            <asp:Label ID="lbl_projcomp" runat="server" Text="                                              % Project Completion"  Width ="345px">
            <asp:TextBox ID="txt_projcomp" runat="server" CssClass="textbox">
       
        </p> 
           
        <p>
            <asp:Label ID="lbl_tcid" runat="server" Text="TC ID" Width ="150px">
            <asp:TextBox ID="txt_tcid" runat="server" CssClass="textbox" >

            <asp:Label ID="Label11" runat="server" Text="                                              Support for Other Domains"  Width ="345px">
            <asp:TextBox ID="txt_sprtdom" runat="server" CssClass="textbox">

        </p>
        
         <p>
            <asp:Label ID="lbl_details" runat="server" Text="Details" Width ="150px">
            <asp:TextBox ID="txt_details" runat="server" CssClass="textbox" >

             <asp:Label ID="Label12" runat="server" Text="                                              Remarks"  Width ="345px">
            <asp:TextBox ID="txt_remarks" runat="server" CssClass="textbox">
        </p>

         <p>
            <asp:Label ID="Label2" runat="server" Text="Domain" Width ="150px">
            <asp:TextBox ID="txt_domain" runat="server" CssClass="textbox" >

             <asp:Label ID="Label13" runat="server" Text="                                              number of test cases"  Width ="345px">
            <asp:TextBox ID="txt_notc" runat="server" CssClass="textbox">

        </p>

         <p>
            <asp:Label ID="Label1" runat="server" Text="Planned TC Prep Start Date" Width ="150px">
            <asp:TextBox ID="txt_prepdate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_calprepdate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_calprepdate_Click" />
             
                 <asp:Calendar ID="cal_prepdate" runat="server" Visible="false"  ShowGridLines="true" style="Z-INDEX: 101; LEFT: 300px; POSITION: absolute; TOP: 300px"  autopostback="true" OnSelectionChanged="cal_prepdate_SelectionChanged">
             
             <asp:Label ID="Label14" runat="server" Text="                                       Stream"  Width ="317px">
            <asp:TextBox ID="txt_stream" runat="server" CssClass="textbox">
        </p>

         <p>
            <asp:Label ID="Label3" runat="server" Text="Planned TC Prep End Date" Width ="150px">
            <asp:TextBox ID="txt_prependdate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_prependdate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_prependdate_Click" />
            <asp:Calendar ID ="cal_prenddate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_prenddate_SelectionChanged">

             <asp:Label ID="Label15" runat="server" Text="                                       No. of times Replanned"  Width ="317px">
            <asp:TextBox ID="txt_numreplan" runat="server" CssClass="textbox">
        </p>

         <p>
            <asp:Label ID="Label4" runat="server" Text="Planned Execution Start Date" Width ="150px">
            <asp:TextBox ID="txt_plstdate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_plstdate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_plstdate_Click" />
            <asp:Calendar ID ="cal_plstdate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_plstdate_SelectionChanged" >


             <asp:Label ID="Label16" runat="server" Text="                                       Entry Report Date" Width ="317px">
            <asp:TextBox ID="txt_entrprtdate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_entrprtdate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_entrprtdate_Click" />
            <asp:Calendar ID ="cal_entrrprtdate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_entrrprtdate_SelectionChanged" >
        </p>

         <p>
            <asp:Label ID="Label5" runat="server" Text="Planned Execution End Date" Width ="150px">
            <asp:TextBox ID="txt_plendate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_plendate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_plendate_Click" />
            <asp:Calendar ID ="cal_plendate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_plendate_SelectionChanged">

             <asp:Label ID="Label17" runat="server" Text="                                       Closure Report Date" Width ="317px">
            <asp:TextBox ID="txt_clrprtdate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_clrprtdate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_clrprtdate_Click" />
            <asp:Calendar ID ="cal_clrprtdate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_clrprtdate_SelectionChanged" >
        </p>

         <p>
            <asp:Label ID="Label6" runat="server" Text="Actual Execution Start Date" Width ="150px">
            <asp:TextBox ID="txt_acstdate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_acstdate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_acstdate_Click" />
            <asp:Calendar ID ="cal_acstdate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_acstdate_SelectionChanged">


            <asp:Label ID="Label18" runat="server" Text="                                       Execution Report Date" Width ="317px">
            <asp:TextBox ID="txt_execrprtdate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_execrprtdate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_execrprtdate_Click" />
            <asp:Calendar ID ="cal_execrprtdate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_execrprtdate_SelectionChanged">
        </p>

         <p>
            <asp:Label ID="Label7" runat="server" Text="Actual Execution End Date" Width ="150px">
            <asp:TextBox ID="txt_acendate" runat="server" CssClass="textbox" >
            <asp:ImageButton ID="img_acendate" ImageUrl="~/content/img/calender.gif" runat="server" OnClick="img_acendate_Click" />
            <asp:Calendar ID ="cal_acendate" runat="server" Visible="false" ShowGridLines ="true" OnSelectionChanged="cal_acendate_SelectionChanged">

             <asp:Label ID="Label19" runat="server" Text="                                       Total No. of Requirements                                        in ALM " Width ="317px">
            <asp:TextBox ID="txt_reqalm" runat="server" CssClass="textbox" >
        </p>

        <p>
            <asp:Label ID="Label8" runat="server" Text="UAT Support Effort" Width ="150px">
            <asp:TextBox ID="txt_usupefrt" runat="server" CssClass="textbox" >

             <asp:Label ID="Label20" runat="server" Text="                                              Total No. of Requirements                                               Mapped to TCs in ALM " Width ="345px">
            <asp:TextBox ID="txt_reqmapalm" runat="server" CssClass="textbox" >

        </p>

        <p>
            <asp:Label ID="Label9" runat="server" Text="Test Execution Effort" Width ="150px">
            <asp:TextBox ID="txt_tstexecefrt" runat="server" CssClass="textbox" >

             <asp:Label ID="Label21" runat="server" Text="                                              Total Effort " Width ="345px">
            <asp:TextBox ID="txt_totefrt" runat="server" CssClass="textbox" >

        </p>

        <p>
            <asp:Label ID="Label10" runat="server" Text="Retrofit Effort" Width ="150px">
            <asp:TextBox ID="txt_retefrt" runat="server" CssClass="textbox" >

             <asp:Label ID="Label22" runat="server" Text="                                              Test Planning Effort" Width ="345px">
            <asp:TextBox ID="txt_tstplanefrt" runat="server" CssClass="textbox" >

        </p>

        <p>
            <asp:Label ID="Label23" runat="server" Text="Defects Rejected" Width ="150px">
            <asp:TextBox ID="txt_defrej" runat="server" CssClass="textbox" >

             <asp:Label ID="Label24" runat="server" Text="                                              Pure Development Effort" Width ="345px">
            <asp:TextBox ID="txt_devefrt" runat="server" CssClass="textbox" >

        </p>

        <p>
            <asp:Label ID="Label25" runat="server" Text="Total Count of Planned Report" Width ="150px">
            <asp:TextBox ID="txt_planrprt" runat="server" CssClass="textbox" >

             <asp:Label ID="Label26" runat="server" Text="                                              Total Count of Actual Report" Width ="345px">
            <asp:TextBox ID="txt_actrprt" runat="server" CssClass="textbox" >

        </p>

        <p>
            <asp:Label ID="Label27" runat="server" Text="ALM Requirement Path" Width ="150px">
            <asp:TextBox ID="txt_almreqpath" runat="server" CssClass="textbox" >

             <asp:Label ID="Label28" runat="server" Text="                                              Number of Descope/NA" Width ="345px">
            <asp:TextBox ID="txt_descope" runat="server" CssClass="textbox" >

        </p>

        <p>
            <asp:Label ID="Label29" runat="server" Text="Defect Count" Width ="150px">
            <asp:TextBox ID="txt_defcount" runat="server" CssClass="textbox" >

             <asp:Label ID="Label30" runat="server" Text="                                              ALM LAB Path" Width ="345px">
            <asp:TextBox ID="txt_almlabpath" runat="server" CssClass="textbox" >

        </p>
        
          <asp:Button ID ="btn_save" runat="server"  Text ="Save" CssClass="btn" Text-align ="Center" width="100px" Height="40px" color="Red"  FontColor="Red" cursor ="Pointer" font-weight ="Bold" BorderColor="Red" BorderWidth ="1px" Margin-left="750px" OnClick="btn_save_Click"/>
          <asp:Button ID ="btn_submit" runat="server"  Text ="Submit" CssClass="btn" Text-align ="Center" width="100px" Height="40px" color="Red"  FontColor="Red" cursor ="Pointer" font-weight ="Bold" BorderColor="Red" BorderWidth ="1px"  OnClick="btn_submit_Click"/>

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