1 · Container Queries

The card responds to its container width, not the viewport. Drag the bottom-right handle to resize the box — the card switches between stacked and wide layouts.

Adaptive Card
I reflow based on my container.
state

↔ Drag the dashed box's corner to resize.

2 · The :has() Selector

The field border + hint react to the input's own validity using :has() — a parent reacting to a child. The submit button disables itself if any field is invalid.

Enter a valid email address
Enter a number ≥ 1

3 · <dialog> & Popover API

Native modal + non-modal overlays — focus trap, ESC to close, backdrop, and light-dismiss, all without JavaScript positioning.

Native dialog

This is a real <dialog> with a backdrop, focus trap, and ESC-to-close — zero positioning CSS.

4 · Scroll-Driven Animations

The top bar tracks scroll progress and items fade in as they enter view — driven by animation-timeline, running on the compositor with no JS. (Falls back gracefully where unsupported.)

Scroll me ↓
Item 2
Item 3
Item 4
Item 5
Item 6
Item 7 — you reached the end

5 · color-mix()

Generate tints, shades, and alpha variants from one base color — no preprocessor. Pick a base and move the slider.