Add CSS page margins for 1000px viewports in MediaWiki's MinervaNeue skin

Wikimedia

MediaWiki has an extension called MobileFrontend which uses a skin called MinervaNeue. This task is about MinervaNeue.

=== Steps to Reproduce

Change your viewport to responsive, 1000px wide. You can do this via your web browser's developer tools. (For example in Firefox: Tools → Web Developer → Responsive Design Mode.)
Visit https://en.m.wikipedia.org/wiki/Arkansas_Timberlands

=== Expected Results

Consistent minimum margins no matter the viewport size.

=== Actual Results

No margins.

Define a width of 90% alongside the existing max-width definition.

You are expected to provide a patch in Wikimedia Gerrit. See https://www.mediawiki.org/wiki/Gerrit/Tutorial for how to set up Git and Gerrit.

Jakub