The layout is saved in localStorage. If you clear cache and site data (called “Cookies and other site data” in Chrome) and reload the page, the layout should reset.
You can also manually do it using the browser dev tools if you know how to. The key is called challenge-layout.
https://developer.chrome.com/docs/devtools/storage/localstorage
Or run localStorage.clear() from the browser console (it will clear all, so be aware of that).