Design Change after selectedindex change of dropdown in update panel

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When iam changing the selected index of a dropdown inside update panel the design of controls changing.Please Help

<div class="grid-24">
               <div class="box">
                   <asp:UpdatePanel ID="UpdatePanel4" runat="server">
                       <Triggers>
                       </Triggers>
                       <ContentTemplate>
                           <div class="form uniformForm">
                               <h3>
                                   Educational History</h3>
                               <div class="field-group">
                                   <div class="field">
                                       <label for="file_name">
                                           Course:
                                           <asp:RequiredFieldValidator ID="RequiredFieldValidator14" runat="server" ControlToValidate="ddlPrevEduCourse"
                                               Font-Bold="false" Font-Size="Small" ValidationGroup="PrevEdu" ForeColor="Red"
                                               ErrorMessage="*"></asp:RequiredFieldValidator></label>
                                       <asp:DropDownList ID="ddlPrevEduCourse" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlPrevEduCourse_SelectedIndexChanged"
                                           ValidationGroup="PrevEdu">
                                       </asp:DropDownList>

                                   </div>
                                   <div class="field">
                                       <label for="file_name">
                                           Stream:
                                           </label>
                                       <asp:DropDownList ID="ddlPrevEduStream" runat="server" ValidationGroup="PrevEdu">
                                       </asp:DropDownList>
                                   </div>
                               </div>
                               <div class="field-group">
                                   <div class="field">
                                       <label for="file_name">
                                           Board/University:
                                           <asp:RequiredFieldValidator ID="RequiredFieldValidator15" InitialValue="0" runat="server"
                                               ControlToValidate="ddlPrevEduUniversity" Font-Bold="false" Font-Size="Small"
                                               ValidationGroup="PrevEdu" ForeColor="Red" ErrorMessage="*"></asp:RequiredFieldValidator></label>

                                       <asp:DropDownList ID="ddlPrevEduUniversity" runat="server" ValidationGroup="PrevEdu">
                                       </asp:DropDownList>
                                   </div>
                                   <div class="field">
                                       <label for="file_name">
                                           Completion Year:
                                           <asp:RequiredFieldValidator ID="RequiredFieldValidator20" runat="server" InitialValue="0"
                                               ControlToValidate="ddlPrevEduCompletionYear" Font-Bold="false" Font-Size="Small"
                                               ValidationGroup="PrevEdu" ForeColor="Red" ErrorMessage="*"></asp:RequiredFieldValidator></label>
                                       <asp:DropDownList ID="ddlPrevEduCompletionYear" runat="server" ValidationGroup="PrevEdu">
                                       </asp:DropDownList>


                                   </div>
                               </div>
                               <div class="field-group">
                                   <div class="field">
                                       <label for="file_name">
                                           Institution:
                                           <asp:RequiredFieldValidator ID="RequiredFieldValidator16" runat="server" ControlToValidate="txtPrevEduInstitution"
                                               Font-Bold="false" Font-Size="Small" ValidationGroup="PrevEdu" ForeColor="Red"
                                               ErrorMessage="*"></asp:RequiredFieldValidator></label>
                                       <asp:TextBox ID="txtPrevEduInstitution" runat="server" type="text" Width="180"></asp:TextBox>
                                   </div>
                                   <div class="field">
                                       <label for="file_name">
                                           Percentage:
                                           <asp:RequiredFieldValidator ID="RequiredFieldValidator17" runat="server" ControlToValidate="txtPrevEduPercentage"
                                               Font-Bold="false" Font-Size="Small" ValidationGroup="PrevEdu" ForeColor="Red"
                                               ErrorMessage="*"></asp:RequiredFieldValidator>
                                       </label>
                                       <asp:TextBox ID="txtPrevEduPercentage" runat="server" type="text" Width="180"></asp:TextBox>
                                   </div>

                                   <div class="field">
                                       <label for="file_name">
                                           <asp:RequiredFieldValidator ID="RequiredFieldValidator19" runat="server" ControlToValidate="ddlPrevEduCompletionYear"
                                               Font-Bold="false" Font-Size="Small" ValidationGroup="PrevEdu" ForeColor="Red"
                                               ErrorMessage=""></asp:RequiredFieldValidator>
                                           .
                                       </label>
                                       <div class="widget widget-table" style="width: 420px;">

                                           <div class="widget-content">
                                               <asp:ListView ID="lvwListingEdu" runat="server" OnItemCommand="lvwListingEdu_ItemCommand"
                                                   OnItemDeleting="lvwListingEdu_ItemDeleting">

                                                   <LayoutTemplate>
                                                       <table class="table table-bordered table-striped data-table">
                                                           <thead>
                                                               <tr>
                                                                   <th>
                                                                       Course
                                                                   </th>
                                                                   <th>
                                                                       University
                                                                   </th>
                                                                   <th>
                                                                       Institution
                                                                   </th>
                                                                   <th>
                                                                       Percentage
                                                                   </th>
                                                                   <th>
                                                                       Duration
                                                                   </th>
                                                                   <th>
                                                                       Action(s)
                                                                   </th>
                                                               </tr>
                                                           </thead>
                                                           <tbody>
                                                               <tr id="ItemPlaceholder"  runat="server">
                                                               </tr>
                                                           </tbody>
                                                       </table>
                                                   </LayoutTemplate>
                                                   <ItemTemplate>
                                                       <tr class="gradeA">
                                                           <td>
                                                               <%#Eval("Course")%>
                                                           </td>
                                                           <td>
                                                               <%#Eval("University_Or_Board")%>
                                                           </td>
                                                           <td>
                                                               <%#Eval("Institution")%>
                                                           </td>
                                                           <td>
                                                               <%#Eval("Percentage_Of_Marks")%>
                                                           </td>
                                                           <td>
                                                               <%#Eval("Duration")%>
                                                           </td>
                                                           <td class="center">

                                                               <asp:LinkButton ID="lbtnDeleteEdu" runat="server" CommandName="Delete" CommandArgument='<%#Eval("Id") %>'>Delete</asp:LinkButton>
                                                           </td>
                                                       </tr>
                                                   </ItemTemplate>
                                               </asp:ListView>
                                           </div>
                                       </div>
                                   </div>
                               </div>
                               <div id="Div2"  runat="server" class="actions" style="padding-left: 290px;">
                                   <asp:Button ID="btnAddPrevEducation" runat="server" Text="Add" type="submit" class="btn btn-primary"
                                       OnClick="btnAddPrevEducation_Click" />
                                   <asp:Button ID="btnClearPrevEdu" runat="server" Text=" Clear" type="submit" class="btn btn-warning"
                                       OnClick="btnClearPrevEdu_Click" />
                               </div>
                           </div>
                       </ContentTemplate>
                   </asp:UpdatePanel>
               </div>
           </div>
           <div class="grid-24">
               <div class="box">
                   <div class="form uniformForm">
                       <div id="DivActionAll"  runat="server" class="actions">
                           <asp:Button ID="btnSaveAll" ValidationGroup="Register" runat="server" Text=" Save"
                               type="submit" class="btn btn-primary" OnClick="btnSaveAll_Click" />
                           <asp:Button ID="btnCancellAll" runat="server" Text=" Cancel" type="submit" class="btn btn-warning"
                               OnClick="btnCancellAll_Click" />
                       </div>
                   </div>
               </div>
           </div>