diff --git a/scripts/check_observability_ui.py b/scripts/check_observability_ui.py
index 9381326..781f306 100644
--- a/scripts/check_observability_ui.py
+++ b/scripts/check_observability_ui.py
@@ -140,6 +140,22 @@ REQUIRED_BASE_SNIPPETS = [
     "momo-observability-mode",
     "/observability/overview",
     "/observability/api/health_indicator",
+    "momo-obs-link",
+    "momo-obs-badge",
+    "classList.add('is-alert')",
+]
+
+FORBIDDEN_BASE_PATTERNS = [
+    Rule(
+        "inline_obs_badge_style",
+        re.compile(r"id=\"momo-obs-badge\"[^>]*style=", re.IGNORECASE | re.DOTALL),
+        "Topbar 觀測台 badge 不得使用 inline style；請使用 .momo-obs-badge。",
+    ),
+    Rule(
+        "hardcoded_obs_alert_color",
+        re.compile(r"(#dc3545|link\.style\.color|badge\.style\.display)", re.IGNORECASE),
+        "Topbar 觀測台告警狀態不得用 JS/inline 硬改色；請切換 is-alert / hidden。",
+    ),
 ]
 
 
@@ -192,6 +208,23 @@ def scan_required_snippets(relative_path: Path, snippets: list[str], label: str)
     return findings
 
 
+def scan_base_topbar() -> list[str]:
+    path = ROOT / BASE_PATH
+    if not path.exists():
+        return [f"{BASE_PATH}: missing required base/topbar file"]
+
+    text = path.read_text(encoding="utf-8")
+    findings = scan_required_snippets(BASE_PATH, REQUIRED_BASE_SNIPPETS, "base/topbar")
+    for rule in FORBIDDEN_BASE_PATTERNS:
+        for match in rule.pattern.finditer(text):
+            line = line_number(text, match.start())
+            snippet = match.group(0).replace("\n", " ")[:90]
+            findings.append(
+                f"{BASE_PATH}:{line}: [{rule.code}] {rule.message} ({snippet})"
+            )
+    return findings
+
+
 def scan_shell() -> list[str]:
     path = ROOT / SHELL_PATH
     if not path.exists():
@@ -273,7 +306,7 @@ def main() -> int:
         findings.extend(scan_file(Path(template_path)))
     findings.extend(scan_css())
     findings.extend(scan_shell())
-    findings.extend(scan_required_snippets(BASE_PATH, REQUIRED_BASE_SNIPPETS, "base/topbar"))
+    findings.extend(scan_base_topbar())
     findings.extend(scan_nav_contract())
 
     if findings:
@@ -286,7 +319,7 @@ def main() -> int:
     print(f"- templates checked: {len(TEMPLATE_PATHS)}")
     print(f"- css guardrails checked: {len(REQUIRED_CSS_SNIPPETS)}")
     print(f"- sidebar/nav guardrails checked: {len(REQUIRED_SHELL_SNIPPETS)}")
-    print(f"- base/topbar guardrails checked: {len(REQUIRED_BASE_SNIPPETS)}")
+    print(f"- base/topbar guardrails checked: {len(REQUIRED_BASE_SNIPPETS) + len(FORBIDDEN_BASE_PATTERNS)}")
     print(f"- nav contract checked: {len(OBSERVABILITY_NAV_ITEMS)} pages")
     return 0
 
diff --git a/templates/components/_ewoooc_shell.html b/templates/components/_ewoooc_shell.html
index 65d6d66..f62d016 100644
--- a/templates/components/_ewoooc_shell.html
+++ b/templates/components/_ewoooc_shell.html
@@ -123,6 +123,36 @@
         opacity: 0.68;
         font-size: 0.68rem;
     }
+    .momo-obs-link {
+        position: relative;
+        text-decoration: none;
+    }
+    .momo-obs-link.is-alert {
+        color: #c96442;
+        box-shadow: 0 0 0 3px rgba(201, 100, 66, 0.12);
+    }
+    .momo-obs-badge {
+        position: absolute;
+        top: -0.22rem;
+        right: -0.22rem;
+        min-width: 1.05rem;
+        height: 1.05rem;
+        padding: 0 0.28rem;
+        border-radius: 999px;
+        display: inline-flex;
+        align-items: center;
+        justify-content: center;
+        border: 1px solid rgba(255, 248, 238, 0.86);
+        background: linear-gradient(135deg, #d76a45, #9d4a32);
+        color: #fff8ee;
+        box-shadow: 0 8px 18px rgba(132, 58, 34, 0.26);
+        font-size: 0.62rem;
+        line-height: 1;
+        font-weight: 900;
+    }
+    .momo-obs-badge[hidden] {
+        display: none;
+    }
 </style>
 {% set _scheduler = scheduler_stats|default({}) %}
 {% set _momo_runs = _scheduler.get('momo_task', []) if _scheduler is mapping else [] %}
diff --git a/templates/ewoooc_base.html b/templates/ewoooc_base.html
index 8934e36..fff38db 100644
--- a/templates/ewoooc_base.html
+++ b/templates/ewoooc_base.html
@@ -59,14 +59,9 @@
                     </div>
                 {% endif %}
 
-                <a class="momo-icon-button" href="/observability/overview" title="AI 觀測台" id="momo-obs-link"
-                   style="text-decoration: none; position: relative;">
+                <a class="momo-icon-button momo-obs-link" href="/observability/overview" title="AI 觀測台" id="momo-obs-link">
                     <i class="fas fa-satellite-dish"></i>
-                    <span id="momo-obs-badge"
-                          style="display: none; position: absolute; top: -2px; right: -2px;
-                                 background: #dc3545; color: white; border-radius: 50%;
-                                 font-size: 0.6em; padding: 2px 5px; min-width: 16px;
-                                 text-align: center; line-height: 1;"></span>
+                    <span id="momo-obs-badge" class="momo-obs-badge" hidden></span>
                 </a>
                 <button class="momo-icon-button" type="button" title="說明">
                     <i class="fas fa-circle-question"></i>
@@ -360,11 +355,11 @@
           link.title = d.tooltip || 'AI 觀測台';
           if (d.alert_count > 0) {
             badge.textContent = d.alert_count;
-            badge.style.display = 'inline-block';
-            link.style.color = '#dc3545';
+            badge.hidden = false;
+            link.classList.add('is-alert');
           } else {
-            badge.style.display = 'none';
-            link.style.color = '';
+            badge.hidden = true;
+            link.classList.remove('is-alert');
           }
         } catch (e) { /* silent */ }
       }