[interfixus]

Css is fundamentally breaching the contract by messing in any way whatsoever with content.

[scegit]

You can still do this

input[type="button"]:active { background-image: url('http://www.google-analytics.com/collect?v=1&_v=j23&a=...'); }

https://www.smashingmagazine.com/2014/10/css-only-solution-f...