From https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(technical)#Weird_things:
Several links (including the links to the side menu, the watchlist, the notifications side menu, edit buttons, the "This page has issues" link, the names of articles as presented on the page itself, and possibly others) are all of a sudden slightly bigger, slightly, smaller, or are spaced out differently.
Browser: Chrome
Operating System/Device: Unknown
Reproduced in Google Chrome (42.0.2311.135) on OS X Yosemite logged out/in locally and on enwiki.