As a first step toward evolving the provisioning of content styles in the apps, we should document the various modules used, and what specifically we need them for (e.g., which rules, and/or which kinds of content).
The goal is to move from there to pulling in specific rules in a more targeted way, to reduce pulling in unneeded rules, and avoid breakage from changes unrelated to the apps' needs.
Findings
skins.minerva.base.styles
Added when skins.minerva.base.reset was merged into it. The Android app has been using skins.minerva.base.reset since May 2015 (https://gerrit.wikimedia.org/r/213465). The specific rules needed are TBD.
skins.minerva.content.styles
This is the base stylesheet for page content in the app. It has also been in use since https://gerrit.wikimedia.org/r/213465. All changes to it should be reviewed by apps and RI engineers.
skins.minerva.content.styles.images
This is a new module needed to fix T219411.
mediawiki.page.gallery.styles
Added in https://gerrit.wikimedia.org/r/282437, with the goal of improving the presentation of images contained in MediaWiki's in-page "image galleries" in the apps. The specific rules needed are TBD; possibly, it could just be removed.
mediawiki.skinning.content.parsoid
This is an important module for Parsoid HTML consumers, which re-implements things like auto-numbering counters for references in order to achieve feature parity with PHP parser HTML; however, it is desktop-focused and we should probably narrow down the specific rules we need. Added in https://gerrit.wikimedia.org/r/346756/.
ext.cite.style
Needed for styling references; added in https://gerrit.wikimedia.org/r/248364/.
ext.math.styles
Needed for styling math formulae; added in https://gerrit.wikimedia.org/r/351840/.
ext.timeline.styles
Needed for styling timelines; added in https://gerrit.wikimedia.org/r/357391/.
ext.pygments
Supports syntax highlighting; added in https://gerrit.wikimedia.org/r/392067/.
mobile.app
Contains apps-specific custom snippets to:
- hide IPA "(listen)" parentheticals (ipa.less)
- contain wide images to prevent horizontal page scrolling (imageOverflow.less)
mobile.app.parsoid
An app-specific custom snippet to center images in Parsoid HTML (figure.less)
Historical note
Prior to May 2015 and https://gerrit.wikimedia.org/r/213465, the MobileApp extension was directly referencing .less files from MobileFrontend and pulling them in, and these were in turn pulled into the app via RL. See https://gerrit.wikimedia.org/r/213431.