<table frame="all">
  <tgroup cols="2" colsep="0" rowsep="1">
    <colspec colnum="1" colname="c1" colwidth="50mm" align="left"/>
    <colspec colnum="2" colname="c2" colwidth="20mm" align="right"/>
    <colspec colnum="3" colname="c3" colwidth="20mm" align="char" char="." charoff="20"/>
    <thead>
      <row bgcolor="#90ee90">
        <entry valign="top">Element</entry>
        <entry valign="top">(Z)</entry>
        <entry valign="top">(A)</entry>
      </row>
    </thead>
    <tbody>
      <row bgcolor="#cdcdcd">
        <entry>Hydrogen</entry>
        <entry>1</entry>
        <entry>1.008</entry>
      </row>
      <row>
        <entry>Helium</entry>
        <entry>2</entry>
        <entry>4.0026</entry>
      </row>
      <row bgcolor="#cdcdcd">
        <entry>Lithium</entry>
        <entry>3</entry>
        <entry>6.94</entry>
      </row>
    </tbody>
  </tgroup>
</table>
