Accordion Expand-Collapse

Elements glide smoothly to their new positions and sizes after the layout changes.

Add a "FLIP Layout Animation" (also called a layout animation or First-Last-Invert-Play) to [where].
When the layout changes, each element should glide from its old position to its new one instead of jumping, quick at first and easing gently into place.
Animate with transforms only so the page doesn't reflow on every frame, and switch straight to the new layout for users who prefer reduced motion.

A side panel slides in from the left, right or top edge, pushing or overlaying content.

Add a "Drawer Slide" (also called off-canvas or a side sheet) to [where].
The panel should slide in from the side edge over the content while the page behind dims, quick and smoothly decelerating, and slide back out the same way when closed.
Keep keyboard focus inside the open drawer, close it with Escape or a click on the dimmed area, and return focus to the button that opened it.

A floating menu fades and scales in from the point where its trigger sits.

Add a "Popover / Dropdown Open" animation (also called a menu pop or dropdown scale-fade) to [where].
The menu should fade in while growing slightly out of the corner next to its trigger, quick and crisp, and fade out a little faster when it closes.
Keep it anchored to the trigger, close it with Escape or a click outside, and expose the open state on the trigger for screen readers.

A translucent dark layer fades in behind an overlay to dim the page.

Add a "Backdrop Scrim Fade" (also called an overlay fade or scrim) to [where].
When the overlay opens, a translucent dark layer should fade in softly over the page behind it, a little slower than the overlay itself, and fade out again when it closes.
Keep the scrim dark in both light and dark themes, and stop the page behind it from scrolling or taking clicks while it is shown.

A panel slides up from the bottom edge, often draggable and snapping to heights.

Add a "Bottom Sheet Slide-Up" (also called a bottom drawer or sheet) to [where].
The panel should slide up from the bottom edge while the page behind it dims, decelerating smoothly into place without a bounce.
Play it once each time the sheet opens, slide it back down on close, and keep keyboard focus inside the sheet while it is open.

Slides stay in place and dissolve into each other instead of sliding.

Add a "Carousel Crossfade" (also called a fade slideshow or carousel fade) to [where].
Slides should stay in place and slowly dissolve into one another, the old one fading out while the next fades in at the same time, then hold for a few seconds before the next change.
Loop seamlessly back to the first slide, pause on hover or focus, and don't auto-advance for users who prefer reduced motion.