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<body><span class="vcard"><a class="email" href="mailto:rune@opera.com" title="Rune Lillesveen <rune@opera.com>"> <span class="fn">Rune Lillesveen</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - Cannot attach Shadow root to unregistered custom element name"
href="https://bugs.webkit.org/show_bug.cgi?id=158550">bug 158550</a>
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<td>rune@opera.com
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - Cannot attach Shadow root to unregistered custom element name"
href="https://bugs.webkit.org/show_bug.cgi?id=158550#c7">Comment # 7</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WONTFIX - Cannot attach Shadow root to unregistered custom element name"
href="https://bugs.webkit.org/show_bug.cgi?id=158550">bug 158550</a>
from <span class="vcard"><a class="email" href="mailto:rune@opera.com" title="Rune Lillesveen <rune@opera.com>"> <span class="fn">Rune Lillesveen</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=158550#c2">comment #2</a>)
<span class="quote">> Created <span class=""><a href="attachment.cgi?id=280877" name="attach_280877" title="Reduction">attachment 280877</a> <a href="attachment.cgi?id=280877&action=edit" title="Reduction">[details]</a></span>
> Reduction
>
> It looks like this is an artifact of "contain: content". That's somehow
> forcing the background color to be painted behind content with a negative
> z-index.</span >
contain:content, which includes paint containment, establishes a new stacking context as per <a href="https://drafts.csswg.org/css-containment/#paint-containment">https://drafts.csswg.org/css-containment/#paint-containment</a> which makes the positioned descendant with negative z-index paint of top of the outer element's background.</pre>
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