I width/height poblem in firefox

Question

i have use one table with in td. i put td height 85% and align=center,valign=middle.
here firebox not working the  85% height
it isthe sasmple code



<td align="center" colspan="4" style="width: 100%; background-color:LightGrey" valign="middle" nowrap="nowrap" height="82%">
            <table style="border:solid 1px DarkGray; background-color:White;">
            <tr>
            <td>
                <div width="100%" height="100%">
                    <table>
                    <tr><td><img src="Images/Network.jpg" /></td><td align="left" valign="middle" style="font-size:medium">Use our professional network to stay connected and make new contacts.</td></tr>
                    <tr><td><img src="Images/Link.gif" /></td><td align="left" valign="middle" style="font-size:medium">Use our intricate matching system to link you to the prefect job.</td></tr>
                    <tr><td><img src="Images/online.jpg" /></td><td align="left" valign="middle" style="font-size:medium">Create a career portfolio, and keep it organized and updated online.</td></tr>
                    </table>
                </div>
            </td>
            <td>
                <div  width="100%" height="100%">
                    <table>
                    <tr>
                    <td align="center"  nowrap="nowrap" valign="middle" height="232px" width="423px" style="background-image: url(Images/Login.PNG); background-repeat:no-repeat;">
                    <table>
                    <tr><td align="right"><asp:Label ID="Label1" runat="server" Text="First Name:" Font-Bold="True" Font-Size="13pt" ForeColor="MidnightBlue"></asp:Label></td><td align="left"><asp:TextBox ID="txtFname" runat="server" MaxLength="30" TabIndex="1"></asp:TextBox></td></tr>
                    <tr><td align="right"><asp:Label ID="Label3" runat="server" Text="Last Name:" Font-Bold="True" Font-Size="13pt" ForeColor="MidnightBlue"></asp:Label></td><td align="left"><asp:TextBox ID="txtLname" runat="server" MaxLength="30" TabIndex="2"></asp:TextBox></td></tr>
                    <tr><td align="right"><asp:Label ID="Label4" runat="server" Font-Bold="True" Font-Size="13pt" ForeColor="MidnightBlue" Text="Email:"></asp:Label></td><td align="left"><Vemail:Emailbox ID="txtEmail" Required="false" runat="server" vStyleName="VEMailbox" vMaxLength="50" vTabIndex="3"/></td></tr>
                    <tr><td></td><td><img style ="cursor :pointer" src="Images/Continue.PNG" onclick="javascript:ShowPage();" tabindex="4" /></td></tr>
                    <tr><td></td><td><label>Already a Member,&nbsp;</label><a tabindex="5" href ="ApplicantLogin.aspx" style ="cursor :pointer">Sign In</a></td></tr>
                    </table>
                    </td>
                    </tr>
                    </table>
                </div>
            </td>
            </tr>
            </table>
            </td>