alpha linear-gradient background-image produces dark line at edge

Originator:cvrebert
Number:rdar://19434933 Date Originated:09-Jan-2015
Status:Closed Resolved:18-Jul-2015
Product:Safari Product Version:8.0.2 (10600.2.5)
Classification:UI/Usability Reproducible:Always
 
Summary:
On non-retina screens, at certain viewport widths, an alpha-channel linear background gradient has a dark vertical line at its edge in Safari on OS X.

Steps to Reproduce:
0. Go to a Mac with a non-retina screen.
1. In Safari 8, open http://getbootstrap.com/javascript/#carousel
       or http://bootstrapdocs.com/v3.2.0/docs/javascript/#carousel
2. Resize the window horizontally while observing the right side of the carousel.
3. As you resize, you'll observe a dark vertical line flicker in and out of view (see screenshot).
4. While the line is visible, stop resizing. The line will remain visible.
You can refresh the page or open the same page in a new tab (while keeping the window the same size)
to confirm that the bug is not related to resizing. (It's just necessary to discover what are the
right "magic" window widths where the bug is visible.)

Expected Results:
There should be no dark vertical line at the edge of the alpha-channel gradient.

Actual Results:
At certain sizes, there is a dark vertical line at the edge of the alpha-channel gradient.

Version:
Safari Version 8.0.2 (10600.2.5)
OS X Yosemite 10.10.1 (14B25)

Notes:
If you inspect the
    <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
in the carousel (i.e. the carousel's right arrow)
and disable its "background-image: linear-gradient" CSS styles,
you'll observe that the line disappears, which indicates that the line is due to the gradient.

Original Bootstrap issue: https://github.com/twbs/bootstrap/issues/15205

Configuration:


Attachments:
'carousel.png' was successfully uploaded.

Comments

Fixed!

The WebKit bug has been fixed as of WebKit Nightly r186963.

Equivalent WebKit bug

Equivalent WebKit bug: https://bugs.webkit.org/show_bug.cgi?id=139803


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