Quantum/Stylo

Stylo (a.k.a. Quantum CSS) will integrate Servo's CSS style system into Gecko, such that the style system code can be shared by Gecko and Servo. Stylo V1 will support Firefox on Windows, macOS, and Linux. Android support may ship in a later release.

Stylo is a core part of Project Quantum.

Getting Involved

If you're interested in contributing to Stylo or Servo, drop by the #servo IRC channel on Mozilla's IRC server.

One front where you can help out is adding new properties to Servo's CSS parsing crate. This requires familiarity with Rust, but is otherwise a good way to dip your toes into Servo's style system. To get started, see Servo's CSS property hacking guide for more information.

If you do not know Rust, you can help implement keyword properties. See the Stylo hacking guide for more details. The Stylo hacking guide also has instructions for building Stylo if you wish to play with it yourself. If you know C++, Firefox bug 1277133 has information about easy Gecko bugs that will assist Stylo's integration with Gecko.

Some Stylo bugs that are good for new Servo contributors are tagged on GitHub as “easy” bugs and “less-easy” bugs.

Release Criteria

Stylo should not cause us to regress any CSS feature unless we explicitly decide that regressing that specific feature is acceptable. The existing test suite will be the primary benchmark of this, with cross-validation from an automated analysis and manual QA of the Alexa Top 500 sites.

• Stylo should have zero blocking bugs.
• Stylo should pass all (non-disabled) Gecko reftests and mochitests.
• Stylo should have no more unimplemented properties on the Alexa Top 500 sites than Gecko.
• Stylo's Talos test performance should be faster than or equal to Gecko's.
• Stylo's memory usage (both Talos and beta telemetry) should be less than or equal to Gecko's.
• Stylo's crash rate should be less than or equal to Gecko's.
• Stylo's user engagement ratio (DAU/MAU) should be greater than or equal to Gecko's.

Work Breakdown Structure

• Tests
  • reftests: Shing
  • mochitests: TBD
• Cargo
  • Build Support: Nathan, Ralph
    • Build Stylo: Lars
  • Vendoring Support: Ted, Yehuda
    • Vendor Servo: Lars
• Glue (Gecko/C++/Rust/Servo): Manish, Simon, Xidorn, Michael
• CSS Support
  • CSS Properties: Cameron, Xidorn, Simon, Emilio, Bobby, Brian
  • CSSOM: Xidorn, Simon
• Autoland
  • Servo CI and Autolander: Emily
  • Gecko CI and Autolander: Emily

Bugs

• Stylo meta bug 1243581
• Stylo dependencies

stylo-central

• Run linux64-stylo tests in mozilla-central (bug 1330414)
  • Enable stop-gap vcs sync (bug 1317525)
  • Vendor servo in mozilla-central (bug 1322769)
  • Make all tests green (by skipping or expecting failure)

• Stylo-central meta bug 1330414
• Stylo-central dependencies

No results.

0 Total; 0 Open (0%); 0 Resolved (0%); 0 Verified (0%);

stylo-nightly

• Enable Stylo in Nightly (bug 1330412) (only on Linux first?)
  • Implement parsing of all CSS properties supported by Firefox
  • Fix and enable all tests (without skipping or expecting failure)
  • Fix all crashes and assertion failures
    • Fuzz Stylo
    • Pass BugHunter
  • Manual QA sign-off
    • Smoke test Alexa Top N sites
    • Exploratory testing of browser UI and features

• Stylo-nightly meta bug 1330412
• Stylo-nightly dependencies

Full Query

ID	Priority	Summary	Whiteboard	Keywords	Assigned to
1419158	P3	border width display bug(page zoom + fractional pixels)		regression
1330069	P4	Create Stylo performance tests based on old Gecko style system performance bugs
1320841	P5	[meta] Pass all mochitests for Stylo		meta
1324348	P5	[meta] stylo: Reftest failures		meta
1362908	P5	[meta] stylo: mochitest crashes		meta

5 Total; 5 Open (100%); 0 Resolved (0%); 0 Verified (0%);

stylo-release

• Run experiment comparing Stylo vs Gecko on engagement ratio, performance, crash rate, and memory usage.
• Let Stylo ride the trains
  • Enable Stylo on all platforms (bug stylo-nightly)
    • Pass QA on all platforms (tests, fuzzing, BugHunter)
• Ship Stylo to Release

Links

• Stylo build instructions
• Stylo meeting notes