diff --git a/B05_Profile/B05_Profile_UI_Style_Structures.css b/B05_Profile/B05_Profile_UI_Style_Structures.css
index 21c2781f6..63c9af9cc 100644
--- a/B05_Profile/B05_Profile_UI_Style_Structures.css
+++ b/B05_Profile/B05_Profile_UI_Style_Structures.css
@@ -447,9 +447,10 @@
   text-overflow: ellipsis;
 }
 
-/* 글자는 성공색에 본문색을 섞어 대비 4.5 를 넘김(성공색 그대로는 밝은 테마에서 4.4). */
+/* 연결됨 — 연한 초록 배경 + 초록 테두리 · 글은 본문색 그대로(밝음 · 어두움 같은 토큰). */
 .b05-structure__summary-name.is-assigned {
-  color: color-mix(in srgb, var(--color-success) 65%, var(--color-text));
+  border-color: var(--color-success);
+  background: color-mix(in srgb, var(--color-success) 18%, var(--color-surface));
 }
 
 .b05-structure__summary .b05-route__irregular-btn {
diff --git a/resources/tester/test_173_1_summary_assigned_bg.py b/resources/tester/test_173_1_summary_assigned_bg.py
new file mode 100644
index 000000000..5067ce2f7
--- /dev/null
+++ b/resources/tester/test_173_1_summary_assigned_bg.py
@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+"""PLAN 173-1 — 집계 항목 연결 라벨 = 글자색 대신 연한 초록 배경 + 테두리(소스 시험)."""
+
+import os
+import re
+
+ROOT = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+CSS = os.path.join(ROOT, "B05_Profile", "B05_Profile_UI_Style_Structures.css")
+
+
+def _rule(sel: str) -> str:
+    src = open(CSS, encoding="utf-8").read()
+    m = re.search(re.escape(sel) + r"\s*\{([^}]*)\}", src)
+    assert m, sel
+    return m.group(1)
+
+
+def test_연결됨_배경_테두리_성공색_글자색_없음():
+    body = _rule(".b05-structure__summary-name.is-assigned")
+    assert re.search(r"border-color:\s*var\(--color-success\)", body)
+    assert re.search(r"background:\s*color-mix\([^;]*--color-success[^;]*--color-surface", body)
+    assert not re.search(r"(^|[;\s])color:", body)