AJAX :: Floating Divs In TabContainer

I am having a problem floating div's inside the AJAX TabContainer. The content I place inside the TabPanel is jumping outside the border. Here is the code:

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="EquipmentDetails.aspx.cs" Inherits="DocumentSandbox.Web.WebForm4" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</asp:ToolkitScriptManager>
<asp:TabContainer ID="TabContainer1" runat="server" ActiveTabIndex="0">
<asp:TabPanel runat="server" HeaderText="TabPanel1" ID="TabPanel1">
<ContentTemplate>
<div>
<div>
<div><div>ID:</div><div>
<asp:TextBox ID="txtID" runat="server" CssClass="criteriatextbox"></asp:TextBox></div></div>
<div><div>Phone Number:</div><div>
<asp:TextBox ID="txtPhoneNumber" runat="server" CssClass="criteriatextbox"></asp:TextBox></div></div>
<div><div>Address:</div><div>
<asp:TextBox ID="txtAddress" runat="server" CssClass="criteriatextbox"></asp:TextBox></div></div>
</div>
<div>
<div><div>Last Name:</div><div>
<asp:TextBox ID="txtLastName" runat="server" CssClass="criteriatextbox"></asp:TextBox></div></div>
<div><div>First Name:</div><div>
<asp:TextBox ID="txtFirstName" runat="server" CssClass="criteriatextbox"></asp:TextBox></div></div>
<div><div>Middle Name:</div><div>
<asp:TextBox ID="txtMiddleName" runat="server" CssClass="criteriatextbox"></asp:TextBox></div></div>
</div>
</div>
</ContentTemplate>
</asp:TabPanel>
<asp:TabPanel ID="TabPanel2" runat="server" HeaderText="TabPanel2">
</asp:TabPanel>
</asp:TabContainer>
</asp:Content>

Here is the css for this code segment:

.searchcriteria
{
}
.searchresults
{
clear: both;
}
.criteriacolumn
{
float:left;
width:500px;
}
.criteriarow
{
width:498px;
height:24px;
padding-bottom:2px;
}
.criteriatextbox
{
padding-top: 3px;
float:left;
width:285px;
}
.criterialabel
{
width:200px;
padding-right: 6px;
text-align:right;
float:left;
}

I found a possible solution here: [URL], but I'm hoping for another option before I give up on having a border.