CSS reset

A base stylesheet for ADG.

Installation

yarn add @atlaskit/css-reset

Usage

View documentation.

Standalone scrollbar appearance

Products that do not consume the full CSS reset can import only the harmonized scrollbar styles:

import '@atlaskit/css-reset/scrollbars.css';

The stylesheet remains inactive until the product adds data-scrollbar-harmonisation to the document root. Products own feature-gate evaluation and attribute cleanup. Tracks are always transparent; no separate transparency attribute is needed.

Only colors change: the thumb uses color.background.accent.gray.subtle and the track is transparent, set once with scrollbar-color on the root and inherited. Scrollbar size, visibility and overlay behavior stay native, so operating system preferences such as macOS "When scrolling" are honored and apply live when changed. Custom WebKit scrollbar sizing is not used because browsers never draw it as an overlay. Browsers without scrollbar-color support keep native colors. Forced colors use browser colors.

In Chromium, a non-auto scrollbar-color disables ::-webkit-scrollbar styles on the same element. Components that own a custom WebKit scrollbar should set their own scrollbar-color, or scrollbar-color: auto, on their scroll container.

The subtle token has approximately 3.24:1 contrast against the white page surface in light mode and 2.85:1 against the #1F1F21 page surface in dark mode; contrast is lower on raised and overlay surfaces. This contrast is accepted for the harmonized treatment, which is not a claim of accessibility conformance. Painted width and allocated width are not a target-size conformance assessment.

Avoiding a flash of un-harmonized scrollbars on SSR pages

The attributes above are normally installed on document.documentElement at runtime by useScrollbarHarmonisation (@atlaskit/app-provider/use-scrollbar-harmonisation). On a server-rendered page that hook only runs client-side, so scrollbars briefly render un-harmonized until the effect fires. Products that render <html> from a server-side template can instead call getScrollbarHarmonisationHtmlAttrs (@atlaskit/app-provider/get-scrollbar-harmonisation-html-attrs) and spread its result onto the server-rendered <html> element, so the attributes — and therefore these CSS rules — are present from the very first paint.