The issue exists only in Timeless skin.

This is also happening with Modern skin.

This is introduced by CodeMirror for some reason:

.wikiEditor-ui-toolbar, .oo-ui-popupWidget.ve-init-mw-switchPopupWidget {
z-index: 7;
}

https://gerrit.wikimedia.org/g/mediawiki/extensions/CodeMirror/+/master/resources/ext.CodeMirror.less

Reason: https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/CodeMirror/+/0676a5263e7db93de5aedd71293227e31fcf84fa%5E%21/resources/ext.CodeMirror.less

Do we have consistent guidelines anywhere for content vs chrome layering and z-index recommended ranges?

Modern skin will have a transparency issue with VE toolbar too:

Specifically, that's Echo/Notifications, another extension. Is this echo/toolbar thing happening with everything, or just modern?

In T200148#4473418, @Etonkovidova wrote:

Modern skin will have a transparency issue with VE toolbar too:

Please file a separate ticket for that, on the WE2017/Echo/Modern tags. Its different from this.

In T200148#4472797, @Isarra wrote:

Do we have consistent guidelines anywhere for content vs chrome layering and z-index recommended ranges?

Our policy is that we try to avoid z-index in favor of dom order (whenever possible).

Our policy is that we try to avoid z-index in favor of dom order (whenever possible).

But when not?

https://www.mediawiki.org/wiki/Manual:Coding_conventions/CSS#z-index

Change 450152 had a related patch set uploaded (by Isarra; owner: Isarra):
[mediawiki/skins/Timeless@master] Prevent content stuff from overlapping over nav stuff

https://gerrit.wikimedia.org/r/450152

Change 450153 had a related patch set uploaded (by Isarra; owner: Isarra):
[mediawiki/skins/Modern@master] Prevent content stuff from overlapping over nav stuff

https://gerrit.wikimedia.org/r/450153

Change 450153 merged by jenkins-bot:
[mediawiki/skins/Modern@master] Prevent content stuff from overlapping over nav stuff

https://gerrit.wikimedia.org/r/450153

Change 450152 merged by jenkins-bot:
[mediawiki/skins/Timeless@master] Prevent content stuff from overlapping over nav stuff

https://gerrit.wikimedia.org/r/450152

@Isarra Thanks for fixing this! I first noticed this as it affected the way my userpage displayed — easy enough fix, nbd — but what's the advantage of having position: relative in #mw_content (already present in Timeless, newly added to Modern) rather than removing it from or adding z-index: 0;to the toolbars, which seem to be the real culprit? Just curious, as it seemed backwards to me.