cssnano removes "all" attribute from css @media query

Question

I am curious if what cssnano does to media queries is ok. In my css file, I have.

@media all and ( min-width: 600px) {}

After running my css through cssnano, it turns it to this >

@media ( min-width: 600px) {}

Is this safe to use in production? I can't seem to find anywhere where it says not having the "all" attribute makes the browser default to all or if not having it is a bad thing for sending the file to production?

Answer 1

I'm the author; yes, it's valid. I'll refer you to the original issue but in a nutshell:

Per the spec (example 5):

I.e. these are identical:

@media all and (min-width:500px) { … }
@media (min-width:500px) { … }

As are these:

@media (orientation: portrait) { … }
@media all and (orientation: portrait) { … }

It seems to me that those could be stripped...[snip]

https://github.com/ben-eb/cssnano/issues/215