1222738 - "unset" does not compute to "initial" for custom properties

Status: RESOLVED INVALID

(Core :: CSS Parsing and Computation, defect)

Description

[philip]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.80 Safari/537.36

Steps to reproduce:

Visit the following codepen:
http://codepen.io/anon/pen/EVdXob


Actual results:

The text was red.


Expected results:

The text should not have been red.

If you change the declaration from `--color: unset` to `--color: initial`, it works. And the spec for unset says that it should compute to "inherit" for inheritable properties, which custom properties are.

https://drafts.csswg.org/css-cascade-4/#valdef-all-unset

Comment 1

[Boris Zbarsky [:bzbarsky]]

I'm not sure I follow.

1)  Custom properties are inheritable properties.
2)  For inheritable properties, 'unset' should compute to 'inherit'.

We agree on those two statements, looks like.  So the behavior of the given testcase, which is:

  <style>
    :root { --color: red; }
    body { --color: unset; }
    p { color: var(--color); }
  </style>
  <p>Some text</p>

should be the the same as this testcase:

  <style>
    :root { --color: red; }
    body { --color: inherit; }
    p { color: var(--color); }
  </style>
  <p>Some text</p>

or, indeed, this testcase:

  <style>
    :root { --color: red; }
    p { color: var(--color); }
  </style>
  <p>Some text</p>

(because that's the whole idea of "unset": make it look as if it's not set at all).  In all of those the text should be 'red'.  Where does 'initial' come into this and why do you think the text should not be red?

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I agree with bz's reasoning.  Given the lack of response, marking as INVALID since I believe our behavior is correct, but if you disagree feel free to reopen with a rationale.

Comment 3

[philip]

Ahh, yes, sorry, you are correct.

And sorry to not reply sooner. I never got an email notification that anyone had replied to the bug.