Why is there a 5-pixel gap between the two upper and lower tables?

Today, we found a problem: there is a 5-pixel gap between the two upper and lower tables.
CodeYes.

<! -- Head -->
<Div align = "center">
<Table width = "778" border = "0" cellpadding = "0" cellspacing = "0">
<Tr>
<TD>
</TD>
</Tr>
</Table>
</Div>
<! -- End head -->
<! -- Menu -->
<Div align = "center">
<Table width = "778" border = "0" cellpadding = "0" cellspacing = "0">
<Tr>
<TD>
</TD>
<TD>
</TD>
<TD>
</TD>
<TD>
</TD>
<TD>
</TD>
</Tr>
</Table>
</Div>
<! -- End menu -->

After debugging, we finally found that the width and height of the image in the head are not set. Change the code below.

<! -- Head -->
<Div align = "center">
<Table width = "778" border = "0" cellpadding = "0" cellspacing = "0">
<Tr>
<TD>
</TD>
</Tr>
</Table>
</Div>
<! -- End head -->
<! -- Menu -->
<Div align = "center">
<Table width = "778" border = "0" cellpadding = "0" cellspacing = "0">
<Tr>
<TD>
</TD>
<TD>
</TD>
<TD>
</TD>
<TD>
</TD>
<TD>
</TD>
</Tr>
</Table>
</Div>
<! -- End menu -->

If there is still an interval, do not leave spaces in the middle of <TD> </TD>.