System specs depend on the Mac's scrollbar setting (narrow-frame wrap at 360px) #271

What happened (2026-11-10). Every local bin/ci started failing spec/system/collection_row_place_spec.rb:93 (spec 048 AC-1.8, "wraps the line at 360px for a five-character set code"). It got a height of 16 where the spec expects ≥ 20. GitHub CI stayed green. The failure blocked every push through the pre-push hook.

Cause. Headless Firefox follows macOS's "Show scroll bars" setting, which defaults to Automatic. With a mouse connected, it draws classic scrollbars, which take 15px of the narrow frame's width. With only the trackpad, it draws overlay scrollbars that take no width. The narrow frame's page always scrolls (816px of content in an 800px frame). With a classic scrollbar, the 360px frame's content is 345px wide and "PMH3A · 146 · Foil · NM · EN" wraps (32px tall). With an overlay scrollbar it's 360px wide and the line fits on one row (16px). CI's Linux Firefox has classic scrollbars.

Fix. Pin ui.useOverlayScrollbars = 0 in spec/support/system.rb's Firefox options, as #118 pinned the colour scheme. Local runs then match CI whatever pointing device is connected.

For the maintainer. On a real 360px phone, which has overlay scrollbars, that line fits with about 8px to spare. So spec 048 AC-1.8's "a five-character code wraps at 360" holds only for a 345px content width. Restating it means a new spec, because shipped specs aren't edited; for example, a longer line, or checking only for no sideways scroll and no place.

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