Software developer, author, and host of Full Stack Radio. November 30, 2017 Update: It looks like the bug in Safari has been fixed in Safari 15, so I wholeheartedly recommend using em for media queries now. Keeping the post up for historical reasons, but the conclusion is no longer valid. In March 2016, Zell Liew published a really great in-depth post titled "PX, EM, or REM Media Queries?", where
![Don't Use Em for Media Queries](https://cdn-ak-scissors.b.st-hatena.com/image/square/991f7ddf684e887941485b560433db24b89d0c88/height=288;version=1;width=512/https%3A%2F%2Fadamwathan.me%2Fimg%2Fpreviews%2Fmedia-query-preview.png)