http://bugs.jqueryui.com/ticket/8442 is currently affecting the template [[de:Vorlage:Gesprochene_Version?useskin=monobook#Vorlage_Gesprochene_Version]].
This can be fixed by updating jquery.ui.core.css to the most recent version from jQuery UI (for all skins, please).
Version: 1.22.0
Severity: normal
URL: https://de.wikipedia.org/wiki/Vorlage:Gesprochene_Version?useskin=monobook#Vorlage_Gesprochene_Version
Is there another test page we can use that doesn't have the workaround? Would be great to reproduce this and test against :) Thanks!
It should be possible to disable that CSS rule in tools like Firebug/Dragonfly/Developer tools etc. or via .ui-helper-clearfix:before, .ui-helper-clearfix:after { border-collapse: separate; } in a user-specific CSS file.
What happens is the following: The template [[de:Vorlage:Gesprochene Version]] contains a table with the attribute "cellspacing=8" (transcluded via [[de:Vorlage:Bausteindesign3}]). This sets the CSS property "border-spacing: 8px", which is an inherited property.
Inside the table, there is the media player control, which uses the CSS class "ui-helper-clearfix". That CSS class in turn is creating a pseudo-element via the rule
.ui-helper-clearfix:before,
.ui-helper-clearfix:after {
content: ""; display: table;
}
in resources/jquery.ui/themes/default/jquery.ui.core.css. This pseudo-element in turn inherits the "border-spacing: 8px" from the outer table.
My edit to [[de:MediaWiki:Common.css]] is not actually a workaround, it's the proper fix that has also been applied to JQuery upstream - cf. https://github.com/jquery/jquery-ui/commit/cb42ee7ccdf6e32be14341a34a037c7f4508c157#themes/base/jquery.ui.core.css