Guix

The package creates three environments: framed, which puts an ordinary frame box around the region, shaded, which shades the region, and leftbar, which places a line at the left side. The environments allow a break at their start (the \FrameCommand enables creation of a title that is “attached” to the environment); breaks are also allowed in the course of the framed/shaded matter. There is also a command \MakeFramed to make your own framed-style environments.