I submitted this bug to blink as well based on a discussion on the WG where it was determined that IE/Blink/Webkit all render the test incorrectly. Here is the info: Safari Versions Tested: 7 & 8 URLs (if applicable) : http://jsbin.com/vaxovufoxi/1/edit?html,output Other browsers tested: Chrome 41: Fail Firefox 36: Pass IE 11: Fail IE Edge (Windows 10 TP): Fail Presto (Opera 12): Pass What steps will reproduce the problem? Go to the jsbin set above, view the three rendered boxes What is the expected result? All three of them should be the same size What happens instead? Testcase 1 and 3 render the same, for some reason setting overflow y to hidden causes the second one to overflow. Please provide any additional information below. Attach a screenshot if possible. I reached out to the WG regarding this to see who was right in this regard. Here is the working group link: https://lists.w3.org/Archives/Public/www-style/2015Mar/0123.html
Chrome Canary 120 and Safari 17.1 matches each other (where 1 & 3 are same but 2 is different) while Firefox Nightly 121 have all three same.