This is based on the TrayLayout2, but it designed to just give exactly
the correct size boxes to fit into a gridfinity system.
It has a modified TrayLayout setup, so it works in one step. It uses
javascript to auto-generate the grid, which means it doesn't currently
work for Inkscape or command line.
* move & refactor JS to static
* add some typing
* move `head` to functions for reusability
* fix wrong separator for `hreflang` value
* fix various html validator errors