Bluffton Middle School’s seventh- and eighth-grade girls’ basketball teams each posted victories over Northfield Thursday. The 40-17 victory by the Tigers’ seventh-grade girls team kept its record unbeaten this season at 9-0. Bridget Steffen had 16 points, with Gracy Fry, Ava Trexler, and Kamryn Ault adding six points each, Kenley Smith scoring four points, and…