Content should fit the display.
On a wide display, header, navigation and footer should be vertical. Left is top, bottom is right.
I’ve already worked out a template for columns that fit the available height, marching into new columns across the available width before starting a new row.
The next step is to use the left and right edges the way top and bottom are typically used.
Except maybe aim header at a square in the top left, if desirable that it not rearrange itself to fit different aspect displays.