This is a clever technique by Dave—use viewport units to make a lightweight lightbox.
This is a terrrific presentation by Chris, going through some practical implementations of modern CSS: logical properties, viewport units, grid, subgrid, container queries, cascade layers, new colour spaces, and view transitions.
One more reason not to use sticky headers on mobile.
Some really great CSS tips from Rich on sizing display text for multiple viewports.
Here’s a nifty demo of popover but it’s not for what we’d traditionally consider a modal dialog.
Such a clever minimalist use of CSS!
The headache of an inconsistent viewport.