diff --git a/cli/engine/browser/injected/index.mjs b/cli/engine/browser/injected/index.mjs
index 91c5370b7..3dfc3c266 100644
--- a/cli/engine/browser/injected/index.mjs
+++ b/cli/engine/browser/injected/index.mjs
@@ -1228,14 +1228,17 @@ if (IS_BROWSER) {
       isHidden: isElementHidden(el),
       findings: findings.map(f => {
         const ap = ANTIPATTERNS.find(a => a.id === (f.type || f.id));
+        const severity = f.severity || ap?.severity || 'warning';
         return {
           type: f.type || f.id,
           category: ap ? ap.category : 'quality',
-          severity: f.severity || ap?.severity || 'warning',
+          severity,
           // Advisory findings (em-dash overuse, etc.) are surfaced but never
           // treated as failures; carry the flag so the overlay/extension can
           // render them with the mildest affordance and consumers can filter.
-          advisory: ap?.severity === 'advisory' || f.severity === 'advisory' || f.advisory === true,
+          // Per-finding promotions override the registry default, so derive
+          // this strictly from the effective severity.
+          advisory: severity === 'advisory',
           detail: f.detail || f.snippet,
           ignoreValue: f.ignoreValue || f.value || '',
           name: ap ? ap.name : (f.type || f.id),
@@ -1293,6 +1296,24 @@ if (IS_BROWSER) {
     catch { return null; }
   }
 
+  function conditionalCssRuleIsActive(rule) {
+    const type = Number(rule?.type);
+    const constructorName = rule?.constructor?.name || '';
+    if (constructorName === 'CSSMediaRule' || type === 4) {
+      const condition = rule.conditionText || rule.media?.mediaText || '';
+      if (!condition || typeof window.matchMedia !== 'function') return true;
+      try { return window.matchMedia(condition).matches; }
+      catch { return true; }
+    }
+    if (constructorName === 'CSSSupportsRule' || type === 12) {
+      const condition = rule.conditionText || '';
+      if (!condition || typeof CSS === 'undefined' || typeof CSS.supports !== 'function') return true;
+      try { return CSS.supports(condition); }
+      catch { return true; }
+    }
+    return true;
+  }
+
   // Read CSS that is absent from document.outerHTML. Inline <style> blocks are
   // already present in the HTML pattern corpus, so limit this walk to linked
   // stylesheets. Flatten grouping rules so each declaration keeps its selector,
@@ -1325,6 +1346,7 @@ if (IS_BROWSER) {
         }
         const isKeyframes = /^\s*@(?:-webkit-)?keyframes\b/i.test(cssText);
         if (hasNestedRules && !isKeyframes) {
+          if (!conditionalCssRuleIsActive(rule)) continue;
           appendRules(nested);
           continue;
         }
diff --git a/cli/engine/detect-antipatterns-browser.js b/cli/engine/detect-antipatterns-browser.js
index a6281bf27..b9424f582 100644
--- a/cli/engine/detect-antipatterns-browser.js
+++ b/cli/engine/detect-antipatterns-browser.js
@@ -8129,14 +8129,17 @@ if (IS_BROWSER) {
       isHidden: isElementHidden(el),
       findings: findings.map(f => {
         const ap = ANTIPATTERNS.find(a => a.id === (f.type || f.id));
+        const severity = f.severity || ap?.severity || 'warning';
         return {
           type: f.type || f.id,
           category: ap ? ap.category : 'quality',
-          severity: f.severity || ap?.severity || 'warning',
+          severity,
           // Advisory findings (em-dash overuse, etc.) are surfaced but never
           // treated as failures; carry the flag so the overlay/extension can
           // render them with the mildest affordance and consumers can filter.
-          advisory: ap?.severity === 'advisory' || f.severity === 'advisory' || f.advisory === true,
+          // Per-finding promotions override the registry default, so derive
+          // this strictly from the effective severity.
+          advisory: severity === 'advisory',
           detail: f.detail || f.snippet,
           ignoreValue: f.ignoreValue || f.value || '',
           name: ap ? ap.name : (f.type || f.id),
@@ -8194,6 +8197,24 @@ if (IS_BROWSER) {
     catch { return null; }
   }
 
+  function conditionalCssRuleIsActive(rule) {
+    const type = Number(rule?.type);
+    const constructorName = rule?.constructor?.name || '';
+    if (constructorName === 'CSSMediaRule' || type === 4) {
+      const condition = rule.conditionText || rule.media?.mediaText || '';
+      if (!condition || typeof window.matchMedia !== 'function') return true;
+      try { return window.matchMedia(condition).matches; }
+      catch { return true; }
+    }
+    if (constructorName === 'CSSSupportsRule' || type === 12) {
+      const condition = rule.conditionText || '';
+      if (!condition || typeof CSS === 'undefined' || typeof CSS.supports !== 'function') return true;
+      try { return CSS.supports(condition); }
+      catch { return true; }
+    }
+    return true;
+  }
+
   // Read CSS that is absent from document.outerHTML. Inline <style> blocks are
   // already present in the HTML pattern corpus, so limit this walk to linked
   // stylesheets. Flatten grouping rules so each declaration keeps its selector,
@@ -8226,6 +8247,7 @@ if (IS_BROWSER) {
         }
         const isKeyframes = /^\s*@(?:-webkit-)?keyframes\b/i.test(cssText);
         if (hasNestedRules && !isKeyframes) {
+          if (!conditionalCssRuleIsActive(rule)) continue;
           appendRules(nested);
           continue;
         }
diff --git a/cli/engine/engines/browser/detect-url.mjs b/cli/engine/engines/browser/detect-url.mjs
index f3ff43c84..ac4bd0a7c 100644
--- a/cli/engine/engines/browser/detect-url.mjs
+++ b/cli/engine/engines/browser/detect-url.mjs
@@ -2,7 +2,7 @@ import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 
-import { finding } from '../../findings.mjs';
+import { deriveAdvisoryFlag, finding } from '../../findings.mjs';
 import { profileFindingsAsync, profileStep, profileStepAsync } from '../../profile/profiler.mjs';
 import { captureVisualContrastCandidate } from '../visual/screenshot-contrast.mjs';
 import { checkContentHiddenAtRest } from '../../rules/checks.mjs';
@@ -394,7 +394,7 @@ async function detectUrl(rawUrl, options = {}) {
     // Per-finding severity promotion (e.g. hero-region pulsing dot)
     // overrides the registry default carried by finding().
     if (f.severity && f.severity !== item.severity) item.severity = f.severity;
-    return item;
+    return deriveAdvisoryFlag(item);
   });
 }
 
diff --git a/cli/engine/engines/static-html/detect-html.mjs b/cli/engine/engines/static-html/detect-html.mjs
index 84e6ab1f5..dac6939b0 100644
--- a/cli/engine/engines/static-html/detect-html.mjs
+++ b/cli/engine/engines/static-html/detect-html.mjs
@@ -9,7 +9,7 @@ import {
 } from '../../design-system.mjs';
 import { isFullPage } from '../../shared/page.mjs';
 import { applyInlineIgnores } from '../../shared/inline-ignores.mjs';
-import { finding } from '../../findings.mjs';
+import { deriveAdvisoryFlag, finding } from '../../findings.mjs';
 import { profileFindings, profileStep, profileStepAsync } from '../../profile/profiler.mjs';
 import {
   checkElementBorders,
@@ -257,7 +257,7 @@ async function detectHtml(filePath, options = {}) {
       // severity (e.g. a pulsing dot inside a header/nav landmark) that
       // overrides the registry default.
       if (f.severity) item.severity = f.severity;
-      findings.push(item);
+      findings.push(deriveAdvisoryFlag(item));
     }
     // Text-content analyzers (em-dash overuse, marketing buzzwords,
     // numbered section markers, aphoristic cadence) live in the regex
diff --git a/cli/engine/findings.mjs b/cli/engine/findings.mjs
index cc7eea776..ae7e134f9 100644
--- a/cli/engine/findings.mjs
+++ b/cli/engine/findings.mjs
@@ -1,9 +1,15 @@
-import { getAntipattern, isAdvisoryRule } from './registry/antipatterns.mjs';
+import { getAntipattern } from './registry/antipatterns.mjs';
 
 function getAP(id) {
   return getAntipattern(id);
 }
 
+function deriveAdvisoryFlag(item) {
+  if (item.severity === 'advisory') item.advisory = true;
+  else delete item.advisory;
+  return item;
+}
+
 function finding(id, filePath, snippet, line = 0) {
   const ap = getAP(id);
   const base = { antipattern: id, name: ap.name, description: ap.description, severity: ap.severity || 'warning', category: ap.category || null, file: filePath, line, snippet };
@@ -11,8 +17,7 @@ function finding(id, filePath, snippet, line = 0) {
   // failures. Carry the flag on the finding so every consumer (CLI, JSON, hook)
   // can partition without a registry lookup. Only stamped when true to keep the
   // finding shape stable for the vast majority of rules.
-  if (isAdvisoryRule(id)) base.advisory = true;
-  return base;
+  return deriveAdvisoryFlag(base);
 }
 
-export { getAP, finding };
+export { getAP, finding, deriveAdvisoryFlag };
diff --git a/tests/detect-antipatterns-browser.test.mjs b/tests/detect-antipatterns-browser.test.mjs
index 471804cb3..967416518 100644
--- a/tests/detect-antipatterns-browser.test.mjs
+++ b/tests/detect-antipatterns-browser.test.mjs
@@ -386,6 +386,8 @@ describe('detectUrl — browser-only fixtures', () => {
     }
     assert.doesNotMatch(snippets, /pass-/, `no pass-case cursor should be flagged, got: ${snippets}`);
     assert.equal(hits.length, 3, `expected 3 blinking-cursor findings, got ${hits.length}: ${snippets}`);
+    assert.equal(hits.every(hit => hit.severity === 'warning'), true, JSON.stringify(hits));
+    assert.equal(hits.some(hit => hit.advisory === true), false, JSON.stringify(hits));
   });
 
   it('typography side-by-side: element-level flag cases get regular overlays', async () => {
diff --git a/tests/fixtures/antipatterns/linked-url-patterns.css b/tests/fixtures/antipatterns/linked-url-patterns.css
index bcc3717d9..b5304d589 100644
--- a/tests/fixtures/antipatterns/linked-url-patterns.css
+++ b/tests/fixtures/antipatterns/linked-url-patterns.css
@@ -15,6 +15,20 @@
   }
 }
 
+/* These selectors exist in the live DOM, but their conditions are inactive.
+   URL scans must not treat their declarations as rendered page styles. */
+@media (max-width: 1px) {
+  .inactive-media-stripes {
+    background: repeating-linear-gradient(45deg, #eee, #eee 10px, #fafafa 10px, #fafafa 20px);
+  }
+}
+
+@supports (display: imaginary-layout) {
+  .inactive-supports-stripes {
+    background: repeating-linear-gradient(45deg, #eee, #eee 10px, #fafafa 10px, #fafafa 20px);
+  }
+}
+
 .unused-linked-transition {
   transition: width 200ms ease;
 }
diff --git a/tests/fixtures/antipatterns/linked-url-patterns.html b/tests/fixtures/antipatterns/linked-url-patterns.html
index 4aceecd16..b75beeb01 100644
--- a/tests/fixtures/antipatterns/linked-url-patterns.html
+++ b/tests/fixtures/antipatterns/linked-url-patterns.html
@@ -9,6 +9,8 @@
   <main>
     <h1>Linked stylesheet pattern</h1>
     <div class="flag-linked-stripes">Rendered repeating stripes</div>
+    <div class="inactive-media-stripes">Inactive media stripes</div>
+    <div class="inactive-supports-stripes">Inactive supports stripes</div>
   </main>
 </body>
 </html>