Let's imagine we've emerged from client meetings with a plan to organize the home page content in three tiers, ranked by importance.
In medium and wide viewports, this content will be laid out in three columns, as shown in the following screenshot:
In a narrow viewport, these will be laid out one after another, in a single vertical column:
And in a small and medium
tablet-width viewport, we'll arrange the content in two side-by-side columns, with the third tier of content laid out beneath it as a horizontal row, ...