Quick, clean, and to the point

Add or remove border horizontal interior

Windows shortcut 

On Windows, this shortcut only works within the Format Cells dialog box, on the Borders tab. If you use this shortcut in Format Cells, you'll see a horizontal interior border added or removed from the border preview area.

On the Mac, there is no equivalent shortcut.

Thank you very much. The function is working fantastically. It saved me at least 3 full working days. - Rajesh
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