To add a border to separate the footer and the body of the survey:

1. Click the Themes tab.
   
2. Click the Edit or Customize Basic Theme icon.
   
3. Select the Footer tab on the left pane.
   
4. Scroll down to the Footer divider  section.
   
5. Click the Footer divider knob to enable and disable the footer divider.
   
6. Select a style.
   
7. Click and drag the slider to adjust the border's width.
   
8. Click the color grid for the border's color.
   
9. Click Save and Apply.