[elteto]

a:b is almost universal as a range designator at this point. / is a _terrible_ choice, especially in a context where a fractional value would also make sense.

That was just an objectively bad syntax choice, but probably keeping on track with CSS.

[lionelw]

Don't you think : is already used for something else in CSS?

[nsonha]

making excuse is easy, here is another one 1..3

[mixmastamyk]

And what’s wrong with whitespace? Like every other property.

[nsonha]

range(1, 3) might be more consistent, it's a single value that is a range and not 2 values.

On a side note: a problem with CSS' claim to be a programming language is that the grammar is not obvious.

[mixmastamyk]

A single value is a choice, two values as well.