title: Center a th regardless of the size of the table
body: <p>I am working on a page that has existing css. I want to add using an existing css colour and shade that is defined for a <code>th</code>.<br>
  Now this <code>th</code> is added as the <strong>last</strong> row on the table.<br>
  What I want is to have any text that appears in this <code>th</code> to be centralised in relation to the enclosing <code>tr</code>.<br>
  What I did so far and somewhat works is to use <code>colspan=7</code> and the content of the <code>th</code> appears somewhat in the center of the row and the table. (There are 14 columns).<br>
  How can I do it without hardcoding numbers in a more generic fashion? I.e. some how center it regardless of the number of columns of the table.</p>