This task is to choose a design and implement the styling for mobile sub-references in the reference list.

Currently references are spaced in PCS output like so,

When subreferences are included, the subref sublist would be shown in a new column according to current flexbox styling which should be reviewed in this task because it looks weird.

One quick approximation to subreferences is shown below, but it unfortunately gets rid of the <li> flexbox so needs to be considered carefully. This is implemented by the WIP patch attached to this task.

The change versus flexbox style is significant, this is the impact of the WIP patch on a normal reflist:

Implementation

Draft patch: https://gerrit.wikimedia.org/r/c/mediawiki/services/mobileapps/+/1185223

We ended up making a smaller change which doesn't affect the flex row layout for normal refs.