合并单元格后，TD的宽度出现差异

合并前代码：.TabDiv
{
overflow: auto;
position: relative;
background-color:Transparent;
width:100%;
display:inline;
}
.Table_Main
{
border-right: 0px;
border-top: 0px;
left: 0px;
border-left: 0px;
width: 100%;
border-bottom: 0px;
position: absolute;
top: 0px;
height: 100%;
        table-layout:fixed;
}
.Div_Main
{
overflow: auto;
position: relative;
background-color:Transparent;

width:100%;
height:100%;
display:inline;
}<body>
    <form id="form1" runat="server">
        <table id="Table_Main" class="Table_Main"> 
            <tr>
                <td>
                    <div id="div_main" class="Div_Main">
                        <table>
                            <tr>
                                <td style="height: 100%">
                                    <div id="Div1" runat="server" class="TabDiv">
                                        <table id="Table4" style="border-style: none; table-layout: fixed; width: 100%" cellpadding="1"
                                            border="1px" bordercolor="black">
                                            <tr>
                                                <td class="TitleTD" style="width: 62px;">
                                                    AAAAAAA
                                                </td>
                                                <td class="InputTD" style="width: 85px;" colspan="1">
                                                    1234567890</td>
                                                <td class="TitleTD" style="width: 145px;">
                                                    ABCDEFGHIJKLMNOPQ</td>
                                                <td class="InputTD" style="width: 125px; height: 21px;">
                                                    &nbsp;</td>
                                                <td class="TitleTD" style="width: 188px; height: 21px;">
                                                    CCCCCCC
                                                </td>
                                                <td class="InputTD" style="width: 216px; height: 21px;">
                                                    &nbsp;</td>
                                            </tr>
                                            <tr>
                                                <td class="TitleTD" style="width: 62px;">
                                                    AAAAAAA
                                                </td>
                                                <td class="InputTD" style="width: 85px;">
                                                    1234567890</td>
                                                <td class="TitleTD" style="width: 145px;">
                                                    ABCDEFGHIJKLMNOPQ</td>
                                                <td class="InputTD" style="width: 125px; height: 21px;">
                                                    &nbsp;</td>
                                                <td class="TitleTD" style="width: 188px; height: 21px;">
                                                    CCCCCCC
                                                </td>
                                                <td class="InputTD" style="width: 216px; height: 21px;">
                                                    &nbsp;</td>
                                            </tr>
                                            <tr>
                                                <td class="TitleTD" style="width: 62px;">
                                                    AAAAAAA
                                                </td>
                                                <td class="InputTD" style="width: 85px">
                                                    1234567890</td>
                                                <td class="TitleTD" style="width: 145px;">
                                                    ABCDEFGHIJKLMNOPQ</td>
                                                <td class="InputTD" style="width: 125px">
                                                    &nbsp;</td>
                                                <td class="TitleTD" style="width: 188px;">
                                                    CCCCCCC
                                                </td>
                                                <td class="InputTD" style="width: 216px">
                                                </td>
                                            </tr> 
                                        </table>
                                    </div>
                                </td>
                            </tr>
                        </table>
                    </div>
                </td>
            </tr>
        </table>
    </form>
</body>合并后并设置合并后单元格的宽度
请指教，怎么就变了呢，该如何处理