Customised sales invoice

Hi Glenn,
Thank you for your help yesterday, I do have another question with regard to the template I have created. I would like the invoice details border to fill the space on the invoice even if there are only 2 item lines within the box. On the template I have moved the 'totals' text box and payment details further down the page and would now like to make the border of the invoice details box drop down to fill the space. I have tried to do this in the editor without success, please could you advise?
Also when I print the document as it is the totals box moves back up?
Many thanks
John