bootstrap为什么是12列

Contrary to the question’s parenthetical, Bootstrap was always at 940px wide, and not 960px, even with the original 16 columns. With the switch to 12 columns in Bootstrap 2, we wanted to simplify the overall grid (16 columns is right on the edge of enough granularity) and make it easier to get three columns.

16-columns has long been the go-to grid for designers and developers, but we’ve noticed a shift to 12- and 24-columns to offer a more flexible layout. And they’re right for doing so—gridded layouts work best with an odd number of  columns (you often see three columns, but four or six are not that popular).