diff --git a/src/main.ts b/src/main.ts
index 0677265..c1fb524 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1254,9 +1254,16 @@ function renderColumnSettings(box: HTMLDivElement, pier: Pier): void {
       B: 'B 단부 · P5 첫 단 · 커플러 1개 (θ + Δθ/2)',
       C: 'C 확대기초 안 · P4 첫 단 · 커플러 2개 · P6 4본',
     };
-    const row = el('div', undefined, 'opts');
+    // 단면 A·B·C in one row (승인 2026-10-26): no wrapping, scrolls sideways on a narrow window.
+    const row = el('div');
+    row.style.display = 'flex';
+    row.style.flexWrap = 'nowrap';
+    row.style.gap = '12px';
+    row.style.overflowX = 'auto';
     for (const kind of ['A', 'B', 'C'] as const) {
       const fig = el('figure', undefined, 'ground-fig');
+      fig.style.margin = '0';
+      fig.style.flex = '0 0 300px';
       fig.innerHTML = columnSectionSvg(kind, input, col);
       fig.appendChild(el('figcaption', captions[kind], 'muted small'));
       row.appendChild(fig);