zoom is uniform, one calculation will do

packages/svelte/src/animate/index.js

@@ -13,14 +13,14 @@ import { cubicOut } from '../easing/index.js';
  */
 export function flip(node, { from, to }, params = {}) {
 	const style = getComputedStyle(node);
-	// need to account for scaled vs unscaled lengths (https://drafts.csswg.org/css-viewport/#scaled).
-	const dsx = from.width / parseFloat(style.width);
-	const dsy = from.height / parseFloat(style.height);
+
+	const zoom = from.width / parseFloat(style.width); // https://drafts.csswg.org/css-viewport/#effective-zoom
 	const transform = style.transform === 'none' ? '' : style.transform;
 	const [ox, oy] = style.transformOrigin.split(' ').map(parseFloat);
-	const dx = (from.left + (from.width * ox) / to.width - (to.left + ox)) / dsx;
-	const dy = (from.top + (from.height * oy) / to.height - (to.top + oy)) / dsy;
+	const dx = (from.left + (from.width * ox) / to.width - (to.left + ox)) / zoom;
+	const dy = (from.top + (from.height * oy) / to.height - (to.top + oy)) / zoom;
 	const { delay = 0, duration = (d) => Math.sqrt(d) * 120, easing = cubicOut } = params;
+
 	return {
 		delay,
 		duration: typeof duration === 'function' ? duration(Math.sqrt(dx * dx + dy * dy)) : duration,