[chente]

Noticed the same thing and found that it was caused by Ghostery.

[bt3]

Yep this was it.

Thanks to all for your concerns of my potentially malware-infected PC, alas, it was just an ad-blocker.

[macintux]

Makes the marketing claim that much more amusing.

> …to speed up page loads, eliminate clutter…

[userbinator]

To be fair, hiding elements may mean not fetching any resources needed for their content, which can be faster despite having to parse a bunch of additional CSS first to determine which ones to hide --- especially if the former involves the execution of JavaScript.

[aasasd]

Loading one snippet from an extension (i.e. the cache) is vastly faster than loading dozens of scripts and styles over the network.

[xeeeeeeeeeeenu]

In my case it was Opera's built-in ad blocker.

[Tarrosion]

What does this mean about Opera's ad blocker? (I also see a ton of junk up top when Opera's block ads is enabled, but I don't know what to make of this.)

[userbinator]

It means that it's more of an ad-hider than a blocker, adding more CSS to hide the relevant elements instead of stripping them out completely (which something like a MITM proxy could easily do.)

[z3t4]

Vanilla Chrome will also inject code if you have a * style rule.