diff --git a/cli/engine/browser/injected/index.mjs b/cli/engine/browser/injected/index.mjs
index 63590867e..1eb350e74 100644
--- a/cli/engine/browser/injected/index.mjs
+++ b/cli/engine/browser/injected/index.mjs
@@ -1283,10 +1283,17 @@ if (IS_BROWSER) {
   function selectorNodesForLiveDom(root, selector) {
     const raw = String(selector || '').trim();
     if (!raw) return null;
-    try {
-      const exact = Array.from(root.querySelectorAll(raw));
-      if (exact.length > 0) return exact;
-    } catch { /* Dynamic/unsupported pseudos get the fallback below. */ }
+
+    const hasPseudoElement = (
+      /::[a-zA-Z-]+(?:\([^)]*\))?|:(?:before|after|first-letter|first-line)\b/i.test(raw)
+    );
+    if (!hasPseudoElement) {
+      // An empty result from a valid full selector is authoritative. In
+      // particular, do not broaden inactive :hover/:focus/:not() rules to
+      // their host element by stripping pseudo-classes.
+      try { return Array.from(root.querySelectorAll(raw)); }
+      catch { return null; }
+    }
 
     // Resolve pseudo-elements to their originating live elements. An attached
     // pseudo-element (`.card::before`) belongs to the element before it, while
@@ -1296,9 +1303,8 @@ if (IS_BROWSER) {
     // invalid selector `main >` and makes absent hosts indistinguishable from
     // selectors the DOM API cannot parse.
     const fallback = raw
-      .replace(/(^|[\s>+~,])::[a-zA-Z-]+(\([^)]*\))?/g, '$1*')
-      .replace(/::[a-zA-Z-]+(\([^)]*\))?/g, '')
-      .replace(/:[a-zA-Z-]+(\([^)]*\))?/g, '')
+      .replace(/(^|[\s>+~,])(?:::[a-zA-Z-]+(?:\([^)]*\))?|:(?:before|after|first-letter|first-line)\b)/gi, '$1*')
+      .replace(/::[a-zA-Z-]+(?:\([^)]*\))?|:(?:before|after|first-letter|first-line)\b/gi, '')
       .trim()
       .replace(/,\s*(?=,|$)/g, '');
     if (!fallback || /^[,\s]*$/.test(fallback)) return null;
@@ -1408,7 +1414,10 @@ if (IS_BROWSER) {
           appendRules(nested, requiresAppliedMatch || isContainerCssRule(rule));
           continue;
         }
-        if (cssText) parts.push(cssText);
+        // Selector-less leaf at-rules (notably @keyframes) cannot be tied to a
+        // rendered node. Their activating selector declarations are already
+        // retained above, while admitting the leaf text would let unused or
+        // conditionally inactive CSS create page-level findings.
       }
     };
     const appendSheet = (sheet) => {
diff --git a/cli/engine/detect-antipatterns-browser.js b/cli/engine/detect-antipatterns-browser.js
index 1cbcf068e..82c211984 100644
--- a/cli/engine/detect-antipatterns-browser.js
+++ b/cli/engine/detect-antipatterns-browser.js
@@ -8187,10 +8187,17 @@ if (IS_BROWSER) {
   function selectorNodesForLiveDom(root, selector) {
     const raw = String(selector || '').trim();
     if (!raw) return null;
-    try {
-      const exact = Array.from(root.querySelectorAll(raw));
-      if (exact.length > 0) return exact;
-    } catch { /* Dynamic/unsupported pseudos get the fallback below. */ }
+
+    const hasPseudoElement = (
+      /::[a-zA-Z-]+(?:\([^)]*\))?|:(?:before|after|first-letter|first-line)\b/i.test(raw)
+    );
+    if (!hasPseudoElement) {
+      // An empty result from a valid full selector is authoritative. In
+      // particular, do not broaden inactive :hover/:focus/:not() rules to
+      // their host element by stripping pseudo-classes.
+      try { return Array.from(root.querySelectorAll(raw)); }
+      catch { return null; }
+    }
 
     // Resolve pseudo-elements to their originating live elements. An attached
     // pseudo-element (`.card::before`) belongs to the element before it, while
@@ -8200,9 +8207,8 @@ if (IS_BROWSER) {
     // invalid selector `main >` and makes absent hosts indistinguishable from
     // selectors the DOM API cannot parse.
     const fallback = raw
-      .replace(/(^|[\s>+~,])::[a-zA-Z-]+(\([^)]*\))?/g, '$1*')
-      .replace(/::[a-zA-Z-]+(\([^)]*\))?/g, '')
-      .replace(/:[a-zA-Z-]+(\([^)]*\))?/g, '')
+      .replace(/(^|[\s>+~,])(?:::[a-zA-Z-]+(?:\([^)]*\))?|:(?:before|after|first-letter|first-line)\b)/gi, '$1*')
+      .replace(/::[a-zA-Z-]+(?:\([^)]*\))?|:(?:before|after|first-letter|first-line)\b/gi, '')
       .trim()
       .replace(/,\s*(?=,|$)/g, '');
     if (!fallback || /^[,\s]*$/.test(fallback)) return null;
@@ -8312,7 +8318,10 @@ if (IS_BROWSER) {
           appendRules(nested, requiresAppliedMatch || isContainerCssRule(rule));
           continue;
         }
-        if (cssText) parts.push(cssText);
+        // Selector-less leaf at-rules (notably @keyframes) cannot be tied to a
+        // rendered node. Their activating selector declarations are already
+        // retained above, while admitting the leaf text would let unused or
+        // conditionally inactive CSS create page-level findings.
       }
     };
     const appendSheet = (sheet) => {
diff --git a/tests/detect-antipatterns-browser.test.mjs b/tests/detect-antipatterns-browser.test.mjs
index d67228d3b..9f5131eb3 100644
--- a/tests/detect-antipatterns-browser.test.mjs
+++ b/tests/detect-antipatterns-browser.test.mjs
@@ -1408,8 +1408,10 @@ describe('detectUrl — browser-only fixtures', () => {
       const containerBackgrounds = await linkedPage.evaluate(() => ({
         inactive: getComputedStyle(document.querySelector('.inactive-container-stripes')).backgroundImage,
         active: getComputedStyle(document.querySelector('.active-container-halo')).backgroundImage,
+        pseudoClass: getComputedStyle(document.querySelector('.inactive-pseudo-stripes')).backgroundImage,
       }));
       assert.equal(containerBackgrounds.inactive, 'none');
+      assert.equal(containerBackgrounds.pseudoClass, '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 }));
@@ -1421,7 +1423,16 @@ describe('detectUrl — browser-only fixtures', () => {
         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 === 'repeating-stripes-gradient'),
+        false,
+        JSON.stringify({ linkedFindings, linkedCssom, containerBackgrounds }),
+      );
+      assert.equal(
+        linkedFindings.some(finding => finding.type === 'gradient-text'),
+        false,
+        JSON.stringify({ linkedFindings, linkedCssom, containerBackgrounds }),
+      );
       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 bcccf003a..36afdbc65 100644
--- a/tests/fixtures/antipatterns/linked-url-patterns.css
+++ b/tests/fixtures/antipatterns/linked-url-patterns.css
@@ -45,6 +45,11 @@ main > ::before {
   }
 }
 
+/* The host exists, but the complete pseudo-class selector is inactive. */
+.inactive-pseudo-stripes:not(.active) {
+  background: repeating-linear-gradient(45deg, #eee, #eee 10px, #fafafa 10px, #fafafa 20px);
+}
+
 .container-query-host {
   container-type: inline-size;
   width: 240px;
@@ -66,6 +71,18 @@ main > ::before {
   }
 }
 
+/* Non-selector at-rules in an inactive container must not enter page-level
+   pattern scans just because their CSSOM text is readable. */
+@container (width > 2000px) {
+  @keyframes inactive-container-gradient-text {
+    from {
+      background: linear-gradient(90deg, #111, #999);
+      background-clip: text;
+    }
+    to { background: none; }
+  }
+}
+
 .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 440c37c34..8fdf9f975 100644
--- a/tests/fixtures/antipatterns/linked-url-patterns.html
+++ b/tests/fixtures/antipatterns/linked-url-patterns.html
@@ -11,6 +11,7 @@
     <div class="flag-linked-grid">Rendered decorative grid</div>
     <div class="inactive-media-stripes">Inactive media stripes</div>
     <div class="inactive-supports-stripes">Inactive supports stripes</div>
+    <div class="inactive-pseudo-stripes active">Inactive pseudo-class stripes</div>
     <div class="container-query-host">
       <div class="inactive-container-stripes">Inactive container-query stripes</div>
     </div>