Created attachment 266740 [details]
Screenshot of incorrect rendering in WebKit Nightly
Steps to reproduce:
1. Open https://bugzilla.mozilla.org/attachment.cgi?id=8665202 in WebKit Nightly
The yellow box should be entirely below (with respect to the Y axis) the blue floating box.
See Chrome Canary screenshot.
IE11 and Firefox Nightly also behave like Chrome Canary.
The blue floating box is entirely within the yellow box.
See WebKit Nightly screenshot.
Analogous Chrome bug: https://code.google.com/p/chromium/issues/detail?id=535381
Originally discovered in: https://bugzilla.mozilla.org/show_bug.cgi?id=1196255
Created attachment 266742 [details]
Screenshot of correct rendering in Chrome Canary
Still broken in Safari Version 9.1 (11601.5.17.1).
Still broken in Tech Preview Release 13 (WebKit 11603.1.5).
Worth noting that this was fixed in Chrome and the patch looks trivial: