Flatpak.org Rewrite

The Flatpak website has been running on Middleman for years and time hasn't been kind. Touching the project resulted in seeing 42 vulnerability warnings. The gem itself hasn't seen an update in ages, and the dependency list is rather large. Very recently, which happens to be 4 years ago, we've done a rebrand to reflect the fact that Flatpak has hit it big. There were a few hints of the old baggage, but overall it didn't feel like a website from 2007. But it was just lipstick. For the layout, I reached for the same named-grid approach we designed for gnome.org. Instead of fighting with a rigid single column you get a multi-column grid with named areas. This allows you to escape the column to span across the whole width or do side-by-side layouts with overflow. Most of the navigation is left to the footer. Another pattern we've embraced elsewhere and has worked well. A major simplification came from the great work of Kolja (razze) on Flathub -- all the distro setup instructions are…