1522967 - Unitless -webkit-transform:perspective(500) is accepted in Chrome and Webkit, but not Firefox.

Status: RESOLVED DUPLICATE of bug 1362499

(Core :: CSS Parsing and Computation, defect, P3)

Description

[Thomas Wisniewski [:twisniewski]]

Attachment: test.html

It turns out that unitless perspective (and perhaps other bits) of CSS transforms are accepted by Chrome and Safari for their webkit-prefixed variants (although they do properly reject them for the standard/unprefixed transform property).

But this acceptance of "unitless perspective" is causing problems with a least one live site, which hides its mobile hamburger menu using such a transform (see https://webcompat.com/issues/21898).

I've attached a reduced test-case showing the basic problem.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

The original testcase didn't directly show the issue, since it had a workaround with unprefixed 'transform' & with pixel units.

Here's an adjusted version without that workaround, which does show the rendering difference.

EXPECTED RESULTS:
No text should be visible. (And the -webkit-transform expression should be accepted & honored.)

ACTUAL RESULTS:
Text is visible (And the -webkit-transform expression is rejected.)

Comment 2

[Daniel Holbert [:dholbert]]

This seems to be a quirk that is specific to -webkit-transform, BTW.

(i.e. Chrome accepts the unitless value in the "-webkit-transform" property alias, but rejects it in the unprefixed 'transform' property)

Comment 3

[Xidorn Quan [:xidorn] UTC+10]

If this is something we want to support, probably we should get compatibility spec document it, otherwise we can probably ask whether Blink and WebKit can drop it.

Chrome Platform Status has an item for this: https://www.chromestatus.com/metrics/feature/timeline/popularity/1672

A popularity of 0.04% is close to their removal criteria IIRC. I wonder whether this number has already taken the existence of standard usage (i.e. the "workaround" mentioned in comment 1) into consideration. If not yet, it is probably likely to be safe to remove for them.

Comment 4

[Thomas Wisniewski [:twisniewski]]

Mike, what do you think?

Comment 5

[Mike Taylor [:miketaylr]]

Edge had implemented this quirk. Let's continue conversation in https://github.com/whatwg/compat/issues/100 to see if Blink feel like they can remove it.

(also, this is a dupe of 1362499)