Background color overrides table border.

I was wondering if I could get some pointers on the following?

 

The below fo renders a table with a header and two rows of alternating
background colors. The table has a single border surrounding the entire
table.

 

When rendered to PDF the background colors of the rows partially overlap the
border of the table. It seems to be consistent on several fo processors, but
differs slightly on the zoom level used in the PDF viewer. If I remove the
background color on the row, the full border thickness is visible again.

 

Thanks

Bob.

 

<?xml version="1.0"?>

<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">

            <fo:layout-master-set>

                        <fo:simple-page-master master-name="simple"
page-height="29.7cm" page-width="21cm" margin-top="1.5cm"
margin-bottom="1.5cm" margin-left="2cm" margin-right="2cm">

                                    <fo:region-body margin-top="1.5cm"/>

                                    <fo:region-before extent="1.5cm"/>

                                    <fo:region-after extent="1.5cm"/>

                        </fo:simple-page-master>

            </fo:layout-master-set>

 

            <fo:page-sequence master-reference="simple">

                        <fo:flow flow-name="xsl-region-body">

 

                                    <fo:table table-layout="fixed"
width="100%" border="2pt solid black">

                                                <fo:table-column
column-width="20mm"/>

                                                <fo:table-column
column-width="20mm"/>

                                                <fo:table-header>

                                                            <fo:table-row>

 
<fo:table-cell>

 
<fo:block>Column1</fo:block>

 
</fo:table-cell>

 
<fo:table-cell>

 
<fo:block>Column2</fo:block>

 
</fo:table-cell>

                                                            </fo:table-row>

                                                </fo:table-header>

                                                <fo:table-body>

                                                            <fo:table-row
background-color="white">

 
<fo:table-cell>

 
<fo:block>Row1</fo:block>

 
</fo:table-cell>

 
<fo:table-cell>

 
<fo:block>Data</fo:block>

 
</fo:table-cell>

                                                            </fo:table-row>

                                                            <fo:table-row
background-color="pink">

 
<fo:table-cell>

 
<fo:block>Row2</fo:block>

 
</fo:table-cell>

 
<fo:table-cell>

 
<fo:block>Data</fo:block>

 
</fo:table-cell>

                                                            </fo:table-row>

                                                </fo:table-body>

                                    </fo:table>

                        </fo:flow>

            </fo:page-sequence>

</fo:root>