The problem appears to be resolved (see comments below).
We are aware of an issue in Chrome 43.0.2357.125 (64-bit) (from the package google-chrome-stable) that results in the page not rendering correctly. It seems to be caused by a bug in either Chrome, or the .deb package (from Google’s homepage).
What’s affected: Only the stable 64 bit version (43.0.2357.125) (installing the 32-bit version on 64-bit Ubuntu worked for me, and the error was not present).
The Bug: Chrome returns/receives a 404 error when trying to load the style.css file for the theme. The file exists, and is reachable in all other browsers at the correct link.
The Fix: For the time being, switching to an older version of Chrome, or to google-chrome-beta, will fix the issue.
Warning: For anyone who has an update for Google Chrome (64-bit) on Ubuntu, I would recommend holding off on said update, or just directly switching to the beta channel.
I have used Chrome’s “report an issue” function to hopefully bring this to Google’s attention. Feel free to do the same.
tl;dr: The issue is coming from this particular version of Chrome, and as such, I can’t/won’t fix it. I’ve brought it to Google’s attention, but using the 32-bit version of Chrome, or the Chrome Beta will fix the issue.