View Transitions, CSS scroll timelines, @starting-style — and when to skip JS.
Gallery → detail morph using document.startViewTransition and view-transition-name.
animation-timeline: view() and scroll() — reveals, progress bar and parallax with no JavaScript.
One stagger animation built in CSS, WAAPI, Motion and GSAP — side by side, with main-thread stress test.
Popover and <dialog> entry/exit animations in pure CSS, including display:none transitions.