Contact emails
 [email protected] <mailto:[email protected]>

Explainer
https://github.com/felipeerias/css-scrollbars-explainer

Specification
https://www.w3.org/TR/css-scrollbars-1

Summary
The CSS Scrollbars spec allows authors to style scrollbars by specifying their 
colors and thickness. This spec adds the following two properties.

The scrollbar-color property provides the capability of changing the color 
scheme of scrollbars so they fit better into the particular style of a web page.

The scrollbar-width property allows the use of narrower scrollbars that may be 
more suitable for some use cases, or even to hide the scrollbars completely 
without affecting scrollability.


Blink component
Blink>Layout>Scrollbars 
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3ELayout%3EScrollbars>

Search tags
css <https://chromestatus.com/features#tags:css>, scrollbars 
<https://chromestatus.com/features#tags:scrollbars>, scrollbar-color 
<https://chromestatus.com/features#tags:scrollbar-color>, scrollbar-width 
<https://chromestatus.com/features#tags:scrollbar-width>

TAG review
https://github.com/w3ctag/design-reviews/issues/563

TAG review status
Issues addressed

Risks


Interoperability and Compatibility
These are already supported inside of Firefox so shouldn't present much of a 
risk. It's possible that if Safari doesn't support them this could lead to some 
level of fragmentation between the legacy pseudo styles and the standard 
properties.


Gecko: Shipped/Shipping (https://bugzilla.mozilla.org/show_bug.cgi?id=1460109) 
Firefox fully supports both properties.

WebKit: Positive (https://github.com/WebKit/standards-positions/issues/133) A 
supportive position has been given for both scrollbar-width and 
scrollbar-color. See also 
https://github.com/WebKit/standards-positions/issues/134

Web developers: Positive (https://insights.developer.mozilla.org 
<https://insights.developer.mozilla.org/>) "Inability to style browser 
scrollbars" included in the list of Top Pain Point Categories of the MDN 
Browser Compatibility Report.

Other signals:

Ergonomics
The value of scrollbar-width influences other properties such as 
scrollbar-gutter which take the scrollbar's thickness as reference.

There might be conflicts between these properties and Chromium's own 
::-webkit-scrollbar pseudo-elements that serve a similar purpose. This is 
partially addressed by these standard properties taking precedence inside of 
Chromium and WebKit.


Activation
These properties are easy for developers to take advantage of many will already 
be using them for Firefox support.


WebView application risks
Does this intent deprecate or change behavior of existing APIs, such that it 
has potentially high risk for Android WebView-based applications?
This should have no impact on WebView applications. It will simply allow 
customising the colours of scrollbars if they apply the necessary styles.


Debuggability
Both properties will show up in dev tools with auto complete support. Scrollbar 
color will also have the color swatch show up for both values.


Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, 
Chrome OS, Android, and Android WebView)?
Yes

Is this feature fully tested by web-platform-tests 
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?
No
The existing Web Platform Tests are not exhaustive. Internal tests are 
implemented where necessary.

Results:
https://wpt.fyi/results/css/css-scrollbars


Flag name on chrome://flags
#enable-experimental-web-platform-features

Finch feature name
ScrollbarColor and ScrollbarWidth

Requires code in //chrome?
False

Tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=891944

Availability expectation
Expect scrollbar-width to be available across all browsers within a year. 
scrollbar-color requires platform changes for WebKit on Apple platforms so may 
take longer to be available.

Adoption expectation
I expect these standard properties be the default way developers choose to 
style both colouring and sizing of scrollbars, replacing the legacy webkit 
pseudo styles for most developers.

Sample links

https://developer.mozilla.org/en-US/docs/Web/CSS/scrollbar-color
https://developer.mozilla.org/en-US/docs/Web/CSS/scrollbar-width

Estimated milestones
Shipping on desktop     121
DevTrial on desktop     118
Shipping on Android     121
DevTrial on Android     118
Shipping on WebView     121


Anticipated spec changes
Open questions about a feature may be a source of future web compat or interop 
issues. Please list open issues (e.g. links to known github issues in the 
project for the feature specification) whose resolution may introduce web 
compat/interop risk (e.g., changing to naming or structure of the API in a 
non-backward-compatible way).
No anticipated spec changes, this is already shipping in Firefox for a long 
time.

Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5665308343795712

Links to previous Intent discussions
Intent to prototype: 
https://groups.google.com/a/chromium.org/g/blink-dev/c/zwG2m_KG0RY/m/8nEx9wCWAwAJ

This intent message was generated by Chrome Platform Status 
<https://chromestatus.com/>.

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