Safari and WebKitGTK have some failures in WPT's web-animations/interfaces/Animation/commitStyles.html: https://wpt.fyi/results/web-animations/interfaces/Animation/commitStyles.html?run_id=5684229927075840&run_id=5715930678034432&run_id=5099062846029824&run_id=5655709666508800 Over in https://github.com/mdn/browser-compat-data/pull/7233#issuecomment-780920038, Brian Birtles looked over the failures and very helpfully broke them down. The conclusion was the issues don't look very severe, but I'm filing this issue so that his analysis can be found from this bug tracker in case someone looks into it. Inlining the comment here too for searchability: - Incorrect handling of logical properties -- fairly minor? - Incorrect handling of custom variables -- probably due to not implementing registered properties -- Firefox also fails this for that reason - Incorrect unit conversion / serialization for em units, line-height, transforms -- only an issue if you are actually reading back the value from style - Incorrect handling of animations in a stack of composited animations -- pretty minor case - Incorrect handling of redundant changes with regards to mutation observers -- edge case