demo · v140

Propagation Chain

Set overscroll-behavior on html AND on body AND on a nested scroll container. The propagation rules say the value propagates from the root to the viewport unless body sets one. Tabulator below shows what the viewport ends up with.

<html>root

<body>pre-140 the propagation source

.scrollernested container

Pre-140: the engine looked at body first, then fell back to a default of auto at the viewport. html was ignored. Post-140: the engine looks at html, propagates to the viewport, and body is just like any other element.

/* Recommended in 140+ */
html { overscroll-behavior: contain; }     /* propagates to viewport */
body { overscroll-behavior: auto; }        /* irrelevant */
.scroller { overscroll-behavior: auto; }   /* nested container, decoupled */

see also