Harry SintonenThe x86css demonstrates complex computation in CSS alone. I can think of couple of interesting applications for this: Since computation is possible this could potentially be used to as a covert side-channel, even when JavaScript execution is disabled.
In addition, several apps and systems also allow uploading custom CSS since it "can't be malicious".
However, I bet there is a lot of limitations how the css can interact with anything else, limiting the impact.
Phil Brass@harrysintonen That “I bet” is doing a lot of heavy lifting