diff --git a/cli/engine/browser/injected/index.mjs b/cli/engine/browser/injected/index.mjs
index f1e90178e..63590867e 100644
--- a/cli/engine/browser/injected/index.mjs
+++ b/cli/engine/browser/injected/index.mjs
@@ -1306,6 +1306,45 @@ if (IS_BROWSER) {
     catch { return null; }
   }
 
+  let containerProbeSequence = 0;
+
+  function isContainerCssRule(rule) {
+    return rule?.constructor?.name === 'CSSContainerRule'
+      || /^\s*@container\b/i.test(rule?.cssText || '');
+  }
+
+  function styleRuleAppliesToLiveMatches(rule, matches) {
+    const style = rule?.style;
+    if (!style || !matches?.length || typeof getComputedStyle !== 'function') return false;
+    const sequence = ++containerProbeSequence;
+    const property = `--impeccable-container-probe-${sequence}-${Math.random().toString(36).slice(2)}`;
+    const value = `impeccable-container-active-${sequence}`;
+    const previousValue = style.getPropertyValue(property);
+    const previousPriority = style.getPropertyPriority(property);
+    try {
+      style.setProperty(property, value, 'important');
+    } catch {
+      return false;
+    }
+
+    const pseudoElements = [...new Set(
+      String(rule.selectorText || '').match(/::[a-zA-Z-]+(?:\([^)]*\))?/g) || [],
+    )];
+    try {
+      return matches.some(el => [null, ...pseudoElements].some(pseudo => {
+        try {
+          const computed = pseudo ? getComputedStyle(el, pseudo) : getComputedStyle(el);
+          return computed.getPropertyValue(property).trim() === value;
+        } catch {
+          return false;
+        }
+      }));
+    } finally {
+      if (previousValue) style.setProperty(property, previousValue, previousPriority);
+      else style.removeProperty(property);
+    }
+  }
+
   function conditionalCssRuleIsActive(rule) {
     const type = Number(rule?.type);
     const constructorName = rule?.constructor?.name || '';
@@ -1321,13 +1360,6 @@ if (IS_BROWSER) {
       try { return CSS.supports(condition); }
       catch { return true; }
     }
-    if (constructorName === 'CSSContainerRule' || /^\s*@container\b/i.test(rule?.cssText || '')) {
-      // The platform exposes no matchMedia-equivalent for container queries,
-      // and selector matches do not prove that the element's query container
-      // satisfies the condition. Omit the group rather than report styles that
-      // are inactive for the current layout.
-      return false;
-    }
     return true;
   }
 
@@ -1341,7 +1373,7 @@ if (IS_BROWSER) {
   function linkedStylesheetText() {
     const parts = [];
     const seen = new Set();
-    const appendRules = (rules) => {
+    const appendRules = (rules, requiresAppliedMatch = false) => {
       for (const rule of rules) {
         if (rule.styleSheet) {
           appendSheet(rule.styleSheet);
@@ -1353,7 +1385,12 @@ if (IS_BROWSER) {
           // Only declarations with a resolvable live host enter the corpus.
           // Unresolvable selectors are uncertain, not evidence that a pattern
           // rendered, and retaining them would leak unused CSS into findings.
-          if (matches?.length > 0) parts.push(cssText);
+          if (
+            matches?.length > 0
+            && (!requiresAppliedMatch || styleRuleAppliesToLiveMatches(rule, matches))
+          ) {
+            parts.push(cssText);
+          }
           continue;
         }
         let nested = [];
@@ -1368,7 +1405,7 @@ if (IS_BROWSER) {
         const isKeyframes = /^\s*@(?:-webkit-)?keyframes\b/i.test(cssText);
         if (hasNestedRules && !isKeyframes) {
           if (!conditionalCssRuleIsActive(rule)) continue;
-          appendRules(nested);
+          appendRules(nested, requiresAppliedMatch || isContainerCssRule(rule));
           continue;
         }
         if (cssText) parts.push(cssText);
diff --git a/cli/engine/detect-antipatterns-browser.js b/cli/engine/detect-antipatterns-browser.js
index d882944c1..1cbcf068e 100644
--- a/cli/engine/detect-antipatterns-browser.js
+++ b/cli/engine/detect-antipatterns-browser.js
@@ -8210,6 +8210,45 @@ if (IS_BROWSER) {
     catch { return null; }
   }
 
+  let containerProbeSequence = 0;
+
+  function isContainerCssRule(rule) {
+    return rule?.constructor?.name === 'CSSContainerRule'
+      || /^\s*@container\b/i.test(rule?.cssText || '');
+  }
+
+  function styleRuleAppliesToLiveMatches(rule, matches) {
+    const style = rule?.style;
+    if (!style || !matches?.length || typeof getComputedStyle !== 'function') return false;
+    const sequence = ++containerProbeSequence;
+    const property = `--impeccable-container-probe-${sequence}-${Math.random().toString(36).slice(2)}`;
+    const value = `impeccable-container-active-${sequence}`;
+    const previousValue = style.getPropertyValue(property);
+    const previousPriority = style.getPropertyPriority(property);
+    try {
+      style.setProperty(property, value, 'important');
+    } catch {
+      return false;
+    }
+
+    const pseudoElements = [...new Set(
+      String(rule.selectorText || '').match(/::[a-zA-Z-]+(?:\([^)]*\))?/g) || [],
+    )];
+    try {
+      return matches.some(el => [null, ...pseudoElements].some(pseudo => {
+        try {
+          const computed = pseudo ? getComputedStyle(el, pseudo) : getComputedStyle(el);
+          return computed.getPropertyValue(property).trim() === value;
+        } catch {
+          return false;
+        }
+      }));
+    } finally {
+      if (previousValue) style.setProperty(property, previousValue, previousPriority);
+      else style.removeProperty(property);
+    }
+  }
+
   function conditionalCssRuleIsActive(rule) {
     const type = Number(rule?.type);
     const constructorName = rule?.constructor?.name || '';
@@ -8225,13 +8264,6 @@ if (IS_BROWSER) {
       try { return CSS.supports(condition); }
       catch { return true; }
     }
-    if (constructorName === 'CSSContainerRule' || /^\s*@container\b/i.test(rule?.cssText || '')) {
-      // The platform exposes no matchMedia-equivalent for container queries,
-      // and selector matches do not prove that the element's query container
-      // satisfies the condition. Omit the group rather than report styles that
-      // are inactive for the current layout.
-      return false;
-    }
     return true;
   }
 
@@ -8245,7 +8277,7 @@ if (IS_BROWSER) {
   function linkedStylesheetText() {
     const parts = [];
     const seen = new Set();
-    const appendRules = (rules) => {
+    const appendRules = (rules, requiresAppliedMatch = false) => {
       for (const rule of rules) {
         if (rule.styleSheet) {
           appendSheet(rule.styleSheet);
@@ -8257,7 +8289,12 @@ if (IS_BROWSER) {
           // Only declarations with a resolvable live host enter the corpus.
           // Unresolvable selectors are uncertain, not evidence that a pattern
           // rendered, and retaining them would leak unused CSS into findings.
-          if (matches?.length > 0) parts.push(cssText);
+          if (
+            matches?.length > 0
+            && (!requiresAppliedMatch || styleRuleAppliesToLiveMatches(rule, matches))
+          ) {
+            parts.push(cssText);
+          }
           continue;
         }
         let nested = [];
@@ -8272,7 +8309,7 @@ if (IS_BROWSER) {
         const isKeyframes = /^\s*@(?:-webkit-)?keyframes\b/i.test(cssText);
         if (hasNestedRules && !isKeyframes) {
           if (!conditionalCssRuleIsActive(rule)) continue;
-          appendRules(nested);
+          appendRules(nested, requiresAppliedMatch || isContainerCssRule(rule));
           continue;
         }
         if (cssText) parts.push(cssText);
diff --git a/tests/detect-antipatterns-browser.test.mjs b/tests/detect-antipatterns-browser.test.mjs
index bc814115d..d67228d3b 100644
--- a/tests/detect-antipatterns-browser.test.mjs
+++ b/tests/detect-antipatterns-browser.test.mjs
@@ -1405,11 +1405,12 @@ describe('detectUrl — browser-only fixtures', () => {
       })));
       const linkedFindings = await linkedPage.evaluate(() => window.impeccableDetect({ serialize: true })
         .flatMap(group => group.findings || []));
-      const inactiveContainerBackground = await linkedPage.$eval(
-        '.inactive-container-stripes',
-        element => getComputedStyle(element).backgroundImage,
-      );
-      assert.equal(inactiveContainerBackground, 'none');
+      const containerBackgrounds = await linkedPage.evaluate(() => ({
+        inactive: getComputedStyle(document.querySelector('.inactive-container-stripes')).backgroundImage,
+        active: getComputedStyle(document.querySelector('.active-container-halo')).backgroundImage,
+      }));
+      assert.equal(containerBackgrounds.inactive, 'none');
+      assert.match(containerBackgrounds.active, /radial-gradient/i);
       const grids = linkedFindings.filter(finding => finding.type === 'codex-grid-background');
       assert.equal(grids.length, 1, JSON.stringify({ linkedFindings, linkedCssom }));
       assert.equal(grids[0].severity, 'advisory');
@@ -1419,6 +1420,7 @@ describe('detectUrl — browser-only fixtures', () => {
         true,
         JSON.stringify({ linkedFindings, linkedCssom }),
       );
+      assert.equal(linkedFindings.some(finding => finding.type === 'radial-halo'), true);
       assert.equal(linkedFindings.some(finding => finding.type === 'repeating-stripes-gradient'), false);
       assert.equal(linkedFindings.some(finding => finding.type === 'layout-transition'), false);
       await linkedPage.close();
diff --git a/tests/fixtures/antipatterns/linked-url-patterns.css b/tests/fixtures/antipatterns/linked-url-patterns.css
index a5cffc1fd..bcccf003a 100644
--- a/tests/fixtures/antipatterns/linked-url-patterns.css
+++ b/tests/fixtures/antipatterns/linked-url-patterns.css
@@ -7,6 +7,11 @@
   }
 }
 
+body {
+  background: #111;
+  color: #fff;
+}
+
 /* A valid hostless pseudo-element selector cannot be queried through the DOM
    selector API. It must remain in the corpus rather than count as unused. */
 main > ::before {
@@ -45,10 +50,20 @@ main > ::before {
   width: 240px;
 }
 
+.container-query-host-active {
+  width: 960px;
+}
+
 @container (width > 900px) {
   .inactive-container-stripes {
     background: repeating-linear-gradient(45deg, #eee, #eee 10px, #fafafa 10px, #fafafa 20px);
   }
+
+  .active-container-halo {
+    width: 640px;
+    height: 400px;
+    background: radial-gradient(circle, rgba(80, 111, 255, 0.85), transparent 70%);
+  }
 }
 
 .unused-linked-transition {
diff --git a/tests/fixtures/antipatterns/linked-url-patterns.html b/tests/fixtures/antipatterns/linked-url-patterns.html
index 7c1cfbe2c..440c37c34 100644
--- a/tests/fixtures/antipatterns/linked-url-patterns.html
+++ b/tests/fixtures/antipatterns/linked-url-patterns.html
@@ -14,6 +14,9 @@
     <div class="container-query-host">
       <div class="inactive-container-stripes">Inactive container-query stripes</div>
     </div>
+    <div class="container-query-host container-query-host-active">
+      <div class="active-container-halo">Active container-query halo</div>
+    </div>
   </main>
 </body>
 </html>