this fixes #1015

src/js/contentscript-end.js

@@ -423,16 +423,18 @@ var uBlockCollapser = (function() {
     // - Injecting a style tag
 
     var addStyleTag = function(selectors) {
-        var selectorStr = selectors.join(',\n');
+        // https://github.com/gorhill/uBlock/issues/1015
+        // Boost specificity of our CSS rules.
+        var styleText = ':root ' + selectors.join(',\n:root ');
         var style = document.createElement('style');
         // The linefeed before the style block is very important: do no remove!
-        style.appendChild(document.createTextNode(selectorStr + '\n{display:none !important;}'));
+        style.appendChild(document.createTextNode(styleText + '\n{display:none !important;}'));
         var parent = document.head || document.documentElement;
         if ( parent ) {
             parent.appendChild(style);
             vAPI.styles.push(style);
         }
-        hideElements(selectorStr);
+        hideElements(styleText);
         messager.send({
             what: 'cosmeticFiltersInjected',
             type: 'cosmetic',

src/js/contentscript-start.js

@@ -97,17 +97,19 @@ var cosmeticFilters = function(details) {
         }
     }
     if ( hide.length !== 0 ) {
-        var text = hide.join(',\n');
+        // https://github.com/gorhill/uBlock/issues/1015
+        // Boost specificity of our CSS rules.
+        var styleText = ':root ' + hide.join(',\n:root ');
         var style = document.createElement('style');
         // The linefeed before the style block is very important: do not remove!
-        style.appendChild(document.createTextNode(text + '\n{display:none !important;}'));
+        style.appendChild(document.createTextNode(styleText + '\n{display:none !important;}'));
         //console.debug('µBlock> "%s" cosmetic filters: injecting %d CSS rules:', details.domain, details.hide.length, hideStyleText);
         var parent = document.head || document.documentElement;
         if ( parent ) {
             parent.appendChild(style);
             vAPI.styles.push(style);
         }
-        hideElements(text);
+        hideElements(styleText);
     }
     vAPI.donthideCosmeticFilters = donthideCosmeticFilters;
     vAPI.hideCosmeticFilters = hideCosmeticFilters;

src/js/scriptlets/cosmetic-logger.js

@@ -64,6 +64,10 @@ if ( injectedSelectors.length === 0 ) {
     return;
 }
 
+// https://github.com/gorhill/uBlock/issues/1015
+// Remove runtime prefix used to augment the specificity of our CSS rules.
+var reSpecificityBooster = /^:root\s+/;
+
 var matchedSelectors = [];
 var selector;
 
@@ -77,7 +81,7 @@ while ( i-- ) {
         continue;
     }
     loggedSelectors[selector] = true;
-    matchedSelectors.push(selector);
+    matchedSelectors.push(selector.replace(reSpecificityBooster, ''));
 }
 
 vAPI.loggedSelectors = loggedSelectors;

src/js/scriptlets/cosmetic-survey.js

@@ -74,8 +74,7 @@ var localMessager = vAPI.messaging.channel('scriptlets');
 localMessager.send({
     what: 'liveCosmeticFilteringData',
     pageURL: window.location.href,
-    filteredElementCount: filteredElementCount,
+    filteredElementCount: filteredElementCount
-    injectedSelectors: injectedSelectors
 }, function() {
     localMessager.close();
 });

src/js/scriptlets/dom-inspector.js

@@ -693,6 +693,9 @@ var cosmeticFilterFromTarget = function(nid, coarseSelector) {
 /******************************************************************************/
 
 var cosmeticFilterMapper = (function() {
+    // https://github.com/gorhill/uBlock/issues/1015
+    var reSpecificityBooster = /^:root\s+/;
+
     // https://github.com/gorhill/uBlock/issues/546
     var matchesFnName;
     if ( typeof document.body.matches === 'function' ) {
@@ -714,7 +717,7 @@ var cosmeticFilterMapper = (function() {
         var i = selectors.length;
         var selector, nodes, j, node;
         while ( i-- ) {
-            selector = selectors[i];
+            selector = selectors[i].replace(reSpecificityBooster, '');
             if ( filterMap.has(rootNode) === false && rootNode[matchesFnName](selector) ) {
                 filterMap.set(rootNode, selector);
                 hideNode(node);