Boost (W3C): When two rendering engines have different behaviors 1. Check the result in a third one. So if you test on WebKit and Blink, please do it in Gecko too 2. Try to find a test on WPT showing the issue https://wpt.fyi 3. Try to find an issue in one of the bug trackers 4. Check what documentations and/or specs are saying This helps find ambiguities, paper cuts, uncertainties, sometimes it even reveals tests which are wrong. It also helps make your site more robust.

When two rendering engines have different behaviors
1. Check the result in a third one. So if you test on WebKit and Blink, please do it in Gecko too
2. Try to find a test on WPT showing the issue https://wpt.fyi
3. Try to find an issue in one of the bug trackers
4. Check what documentations and/or specs are saying
This helps find ambiguities, paper cuts, uncertainties, sometimes it even reveals tests which are wrong. It also helps make your site more robust.

— Karl Dubost (@karlcow@mastodon.cloud)