[Affected versions]: Firefox 65.0a1 (BuildId:20181108100100) [Unffected versions]: Firefox 64.0b7 (BuildId:20181105164654) Firefox 63.0.1 (BuildId:20181030165643) Firefox 60.3.0esr (BuildId:20181017185317) [Affected platforms]: Windows 10 64bit [Steps to reproduce]: 1. Launch Firefox. 2. Bookmark any webpage and observe the library button. [Expected result]: The library button is not displaying a fading animation. [Actual result]: The library button has a fading animation. [Regression range]: This seems to be a recent regression: Last good revision: b9a0d600e885107a741ad7e98a9be6aeb0c6d2b4 First bad revision: a672ddc3be9ff55553aa5ffeead42a505e38bb94 Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=b9a0d600e885107a741ad7e98a9be6aeb0c6d2b4&tochange=a672ddc3be9ff55553aa5ffeead42a505e38bb94 [Notes]: For further information regarding this issue, please observe the attached screencast.

Hi Dao, It seems that mozregression pointed out Bug 1503022 for causing this regression. Can you please have a look? Thanks!

Pushed by dgottwald@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/781581f8c129 Move library-animatable-box into the navigation toolbar so it inherits the right color, and clean up related CSS. r=jaws

I have reproduced this bug with Nightly 65.0a1 (2018-11-09) on Windows 10, 64 Bit ! This bug's fix is Verified with latest Beta ! Build ID 20181220174318 User Agent Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0 [testday-20181221]

Thank you Sajedul for verifying this issue. Marking this accordingly.