Bug 199409 - background-clip:var(--a) invalidates -webkit-background-clip:text when --a:text
Summary: background-clip:var(--a) invalidates -webkit-background-clip:text when --a:text
Status: RESOLVED DUPLICATE of bug 199410
Alias: None
Product: WebKit
Classification: Unclassified
Component: CSS (show other bugs)
Version: WebKit Nightly Build
Hardware: Mac macOS 10.14
: P2 Normal
Assignee: Nobody
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2019-07-02 10:36 PDT by Jim Ratliff
Modified: 2019-07-03 10:14 PDT (History)
0 users

See Also:

Attachments
Screenshot: shows desired and actual rendering by WebKit (223.49 KB, image/png)
2019-07-02 10:36 PDT, Jim Ratliff 		no flags Details
View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Jim Ratliff 2019-07-02 10:36:06 PDT 
Created attachment 373337 [details]
Screenshot: shows desired and actual rendering by WebKit

See http://dabblet.com/gist/062ef5b3cef1557ed994aae73ee6ff8a for reduced test case.

This problem occurs when `background-clip` is set to `text` using a CSS variable. It causes WebKit to ignore a valid `-webkit-background-clip:text` and instead reverts to `background-clip:border-box`.

Note that the following works fine (renders background through clipped text):
  -webkit-background-clip: text;
  background-clip: text;

But the following does not work (computes `background-clip:border-box` rather than `background-clip:text`) in WebKit, Safari, and Chrome (but works fine in Firefox):
  --a: text;  */
  -webkit-background-clip: text;
  background-clip: var(--a);

Apparently, WebKit finds `background-clip: var(--a);` invalid at computed-value time (even though it is equivalent to `background-clip:text`, which works fine) and causes WebKit to throw out the preceding `-webkit-background-clip: text;` statement.
Comment 1 Alexey Proskuryakov 2019-07-03 10:14:45 PDT 

*** This bug has been marked as a duplicate of bug 199410 ***