Created attachment 473373 [details] Screen Recording 1. Visit https://www.bram.us/2024/11/25/experiment-automatically-triggered-view-transitions-with-mutationobserver/#shortcomings 2. Click on the of the lime/hotpink/grey boxes in the embedded demo While the View Transition runs, the entire CodePen embed’s content gets shifted by a pixel. Not sure what is causing this, but it is happening. Note that the View Transition is actually running inside a nested iframe: you have the CodePen embed (which is an iframe) that contains the CodePen UI + the demo (which itself is also in an iframe). It is the outer iframe that is shifting, not just the demo one. See attached screen recording.