This is most probably a browser compatibility issue because even IE10 doesn't have this problem.
01.png: Under normal circumstances, the sidebar goes below the content of the article. The same is repeated for non-mainspace articles accessed via URL or opening links from the topbar ("{{username}}" "my talk" "my preferences" "my watchlist" "my contributions" "log out") in a new tab.
03.png: However, if I directly access (ie. left-click) a link on the topbar or reload the current page normally (F5, Refresh button), this happens. The sidebar and topbar go missing and every link shows up in white text.
04.png: Continuing from 03.png, if I click the Back button in Chromium, the sidebar and topbar still remain missing and the link colour issue remains. Force-refreshing (CTRL+F5; CTRL+click Refresh button) brings me back to 01.png or 02.png.
I'm using Chromium build 201348 on Windows 8. As mentioned above, this problem does not show up in IE9.
EDIT: I just noticed that, whenever I left-click on or normal reload any link on HLP, the site's appearance changes to something that seems like mobile view until I force-refresh (05.png). Again, IE10 doesn't have this issue.
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