Last modified: 2014-09-24 11:39:34 UTC
This happens when the ToC drawer is opened. Also the three lines of the ToC icon don't seem aligned to the three dots of the overflow menu indicator.
Change 159742 had a related patch set uploaded by Dbrant: Fix ToC icon color in Dark mode. https://gerrit.wikimedia.org/r/159742
Change 159742 merged by jenkins-bot: Fix ToC icon color in Dark mode. https://gerrit.wikimedia.org/r/159742
Assuming this is fixed, marking as such.