The center column here is six of twelve columns — a comfortable reading measure — flanked by a three-column rail on each side. On phones everything stacks with the article first, then the left rail's widgets, then the right's, so the mobile page reads top-to-bottom in order of importance.

Two rails make sense when navigation and action both matter on the same page: a documentation portal with a section tree on one side and download links on the other, a magazine hub with categories and a subscribe box, a dashboard-style landing with status on the left and shortcuts on the right.

Give each rail one job. The moment both rails do a bit of everything, readers stop trusting either.

The trade-off is width: at the md breakpoint each rail is only a few words wide, so keep widget titles short and lists tighter than you would on a 4/8 page. If a rail keeps wanting more room, that's the layout telling you it should be the only rail.

This page keeps wayfinding on the left and “what next” on the right — the same division of labor described on the single-rail pages, just given a column each.