diff --git a/A00_Common/design/design_page.css b/A00_Common/design/design_page.css
index 6543b3961..b169717c2 100644
--- a/A00_Common/design/design_page.css
+++ b/A00_Common/design/design_page.css
@@ -93,7 +93,7 @@
 }
 
 /* 횡단 보기 위 평면 겹침 패널(요구 258 · 263 · `design_plan_peek`) — 카드 칸 위에 뜸(자리 안 차지) ·
-   닫히면 손잡이만 위 가운데 · 열면 처음 높이 32 % · 아래 끝 끌어 조절 · 조작은 B05 평면 그대로라
+   닫히면 손잡이만 위 가운데 · 열면 처음 높이 32 %(160 px 아래로 안 감) · 아래 끝 끌어 조절 · 조작은 B05 평면 그대로라
    단추 줄 · 안내 · 상태줄 등만 감춤. */
 .design-plan-peek {
   position: absolute;
@@ -106,7 +106,7 @@
 }
 
 .design-plan-peek.is-open {
-  height: var(--design-plan-peek-height, 32%);
+  height: var(--design-plan-peek-height, max(32%, 160px)); /* 종단 판 펼친 B06 = 칸이 낮음 */
 }
 
 /* 높이 끌기 손잡이 = 패널 아래 끝(공용 세로 손잡이는 위 끝) · 열렸을 때만 */
diff --git a/A00_Common/design/design_plan_peek.ts b/A00_Common/design/design_plan_peek.ts
index 0ff936cae..4767bd789 100644
--- a/A00_Common/design/design_plan_peek.ts
+++ b/A00_Common/design/design_plan_peek.ts
@@ -29,13 +29,14 @@ export function mountPlanPeek(
   body.append(note);
   const handle = createWorkflowPanelHandle("bottom", "up", "평면");
   // 아래 끝 끌어 높이 — 120 px ~ 칸 높이 − 48 px(손잡이 자리) · 두 번 누름 = 처음 높이(32 %)
+  // 칸 = 패널 % 높이가 재는 자리(offsetParent) — `center` 는 높이 0
   const resizer = createPanelResizer({
     axis: "vertical",
     target: root,
     cssVar: "--design-plan-peek-height",
     direction: 1,
     min: 120,
-    max: () => center.clientHeight - 48,
+    max: () => (root.offsetParent?.clientHeight ?? 0) - 48,
     storageKey: stateKey("plan-peek-height") ?? undefined,
   });
   root.append(body, resizer.root, handle.root);
diff --git a/resources/tester/test_258_b06_plan_peek.py b/resources/tester/test_258_b06_plan_peek.py
index 0f7f530a2..d5e12010a 100644
--- a/resources/tester/test_258_b06_plan_peek.py
+++ b/resources/tester/test_258_b06_plan_peek.py
@@ -53,6 +53,7 @@ def test_높이_끌기와_기억() -> None:
     assert "createPanelResizer({" in PEEK
     assert 'cssVar: "--design-plan-peek-height",' in PEEK and "direction: 1," in PEEK
     assert 'storageKey: stateKey("plan-peek-height")' in PEEK
+    assert "max: () => (root.offsetParent?.clientHeight ?? 0) - 48," in PEEK
     assert "resizer.restore();" in PEEK[PEEK.index("const open = async") :]
     state = (ROOT / "A00_Common" / "b_page_state.ts").read_text(encoding="utf-8")
     assert '"plan-peek-height": { bucket: "pref", scope: "global" },' in state
@@ -65,7 +66,9 @@ def test_겹침_자리와_감춤() -> None:
     root = _rule(".design-plan-peek")
     assert "position: absolute;" in root and "z-index: 4;" in root
     assert "pointer-events: none;" in root  # 닫힌 동안 카드 누름 통과
-    assert "height: var(--design-plan-peek-height, 32%);" in _rule(".design-plan-peek.is-open")
+    assert "height: var(--design-plan-peek-height, max(32%, 160px));" in _rule(
+        ".design-plan-peek.is-open"
+    )
     hidden = CSS[CSS.index(".design-plan-peek .b05-routeedit__tools,") :]
     hidden = hidden[: hidden.index("}")]
     for part in ("__tools", "__info", "__measure", "__side-wrap", "b05-contourlock"):