Reduce vertical/horizontal air in the Comments side panel and shrink
body/author/selection font sizes for more comments per screen, scoped to
features/comment/ so the shared aside (TOC/Details tabs) is untouched.
- comment-list-item: author name + selection quote sm->xs, avatar gap xs,
outer pb 6
- comment-list-with-tabs: Paper p/mb sm->xs, reply Divider my 4->2
- comment.module.css: body ProseMirror font-size sm (16->14px), line-height
1.4, margin-top 10->4; .textSelection padding 8->6, margin-top 4->2
Implements docs/backlog/comments-panel-density.md.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
f09becd1bf