Scroll one frame and the rest follow.

Add this to any site you control, just before </body>:

It also keeps the URL field and this page's address pointed at wherever you click to inside a frame.

It does nothing unless the page is framed here, so it is safe to leave on a staging site. Sites without it still work — their frames just scroll on their own. On a BrowserSync dev URL it leaves scrolling to BrowserSync.

Browsers block reading scroll position across origins, which is why the site itself has to opt in.