If I select some text (with or without selecting the paragraph mark) and use the Top border button from the Home tab, I get a box round the selection and not the top border I've requested. Going back to the ribbon, I see the Outside borders option is highlighted, plus the four (top, left, right, bottom) options.

How do I use the border options to apply just a top border?

Windows 2010, 14.0.6114.5000 (32 bit)