Why footer columns got an 'Auto Width' mode outside the 12-grid

The question: The footer Column Ratio slider can't reproduce a real design's columns (a wide brand block beside three content-sized link lists). Do we hit a grid limitation — and if so, do we build a new flex container/section, or fix the existing column control?

Context

Rebuilding a marketing footer, the source band was a plain flex row:

footer .cols { display:flex; justify-content:space-between; gap:40px }
/* children are content-sized: brand ≈280px, then three ~110–128px link lists */

The UnysonPlus footer builder offers a Column Ratio split-slider. It looks free-form — you drag dividers and it shows fractions — and it stores real percentages ({w:30},{w:23},{w:23},{w:24}). But at render time unysonplus_footer_widths_to_grid() snaps every width to the nearest twelfth and reconciles the total to 12:

30% → round(30/100 × 12)=4    23%→3    23%→3    24%→3    total 13
→ largest absorbs −1 → [3,3,3,3] → fw-col-md-3 × 4 = four equal quarters

So 30/23/23/24 renders as 1/4·1/4·1/4·1/4. The grid can express twelfths and (via a special case) fifths — nothing else. "One column slightly wider than three equal ones" is simply not on the twelfths lattice, so the brand block lost all emphasis. The limitation is real.

Options considered

1. Emit the raw percentages (a flex-basis:<w>% per column instead of fw-col-md-N). Unlocks any fixed ratio, small change. But the source isn't a fixed ratio at all — DevTools showed content-sized columns with space-between doing the distribution, not 24/25/25/26. A fixed % would only approximate it and still clump content to the left of each cell.
2. A new flex section/container type with content-sized columns and justify-content. Matches the source's model literally and generalizes, but it's a large new surface (option schema, UI, render, docs, screenshots) for what is, today, one footer band.
3. Add an opt-in "Auto Width" mode to the existing column control. When on, the ratio is ignored: columns become flex:0 0 auto (content-sized) and the row is a flex layout whose spread is a small Distribution select (space-between / around / center / start / end).

Decision

Option 3. unysonplus_footer_columns_field gained an Auto Width (fit to content) switch plus a Distribution select; footer-builder.php bypasses the twelfths snap when it's on, emitting a footer-row--auto flex row (justify-content:var(--fa-justify)) with footer-col--auto content-sized columns. The twelfths ratio stays the default, so no existing footer changes; Auto is purely additive and works on all four bars (pre / main / post / copyright).

Why

• It matches the source's actual layout model, not an approximation — content-hugging columns distributed by the row, which is exactly what justify-content:space-between does. Emitting a fixed % (option 1) would reproduce neither the widths nor the distribution.
• Smallest lever that fully solves it. A whole flex-section container (option 2) is the right home for that model someday, but building it speculatively for one band is the same mistake as swapping a working layout wholesale to gain one thing. Auto mode reuses the entire existing column/element/mobile-stacking machinery; it's one switch, one select, one render branch, ~20 lines of CSS.
• Self-contained and safe. The Auto row/column CSS defines its own flex layout (no dependency on the Bootstrap grid classes it replaces), and the mode is opt-in, so the twelfths default and every saved footer are untouched.

The larger "flex container/section with justify-content" remains a reasonable future feature — but it should be triggered by a real need for content-sized distribution in page content, not built ahead of one.