To do Alt + H B C on Mac in Excel, download and install Accelerator Keys, then press Option, followed by H, B, C.
Command: Top and Thick Bottom Border
This is how to do Alt + H B C on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + H B C top and Thick Bottom Border applies a thin top border and thick bottom border. This combination is often used in financial statements above total rows.