Unfortunately, prefers-reduced-motion is fingerprintable even with Javascript disabled: https://news.ycombinator.com/item?id=30237846 https://news.ycombinator.

Unfortunately, prefers-reduced-motion is fingerprintable even with Javascript disabled: https://news.ycombinator.com/item?id=30237846 https://news.ycombinator.com/item?id=30237846 In addition, "reduced motion" is only a partial solution to the problem of unwanted motion. I would much prefer zero motion. In Firefox, it is possible to disable CSS animations globally, by adding the following to both chrome/userContent.css (with the appropriate namespace header) and chrome/userChrome.css in your profile directory: *, :before, :after { transition: none !important; animation-delay: 0ms !important; animation-duration: 0ms !important; } This also requires setting toolkit.legacyUserProfileCustomizations.stylesheets to true in about:config I have been disabling animation in userContent.css (which affects websites) for years with no problems. More recently, I realized I could also disable it in userChrome.css (which affects the Firefox UI). This exposes what appears to be a race condition bug involving tabs. Occasionally, a tab's close button will stop responding, and that tab will also become impossible to drag to new positions. This can be worked around by attempting to drag a different tab, releasing that drag, then immediately dragging the frozen tab to an empty part of the tab bar, which will unfreeze the tab. I consider this minor annoyance well worth the benefits, which includes disabling animations that would be permitted with prefers-reduced-motion, such as the sliding of the "Find in Page" panel. It is possible that setting an extremely brief animation might avoid the bug without showing visible animation but I have not tested this.