diff --git a/docs/tests/css-selector-based-cosmetic-filters.html b/docs/tests/css-selector-based-cosmetic-filters.html
new file mode 100644
index 000000000..9c1998121
--- /dev/null
+++ b/docs/tests/css-selector-based-cosmetic-filters.html
@@ -0,0 +1,150 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>CSS selector-based cosmetic filters</title>
+<style>
+    .filters {
+        font-family: monospace;
+        white-space: pre;
+    }
+    .tests {
+        align-items: flex-start;
+        display: flex;
+        flex-wrap: wrap;
+    }
+    .tile {
+        display: inline-flex;
+        flex-direction: column;
+        margin: 0 20px 10px 0;
+        min-width: 200px;
+    }
+    .tile div {
+        align-items: center;
+        color: white;
+        display: flex;
+        justify-content: center;
+    }
+    .tile > div {
+        height: 50px;
+        position: relative;
+    }
+    .tile > div > div {
+        height: 100%;
+        left: 0;
+        position: absolute;
+        top: 0;
+        width: 100%;
+    }
+    .tile > code {
+        align-self: center;
+    }
+    .pass {
+        background-color: green;
+    }
+    .pass::before {
+        content: 'pass';
+    }
+    .fail {
+        background-color: red;
+    }
+    .fail::before {
+        content: 'fail';
+    }
+    .tests a, .tests b {
+        display: none;
+    }
+    .tests a::before {
+        opacity: 0;
+    }
+    .tests b::after {
+        opacity: 0;
+    }
+    .fail-pseudo::before {
+        align-items: center;
+        background-color: red;
+        content: 'fail';
+        display: flex;
+        height: 100%;
+        justify-content: center;
+        left: 0;
+        position: absolute;
+        top: 0;
+        width: 100%;
+    }
+</style>
+<script nonce="" src="https://assets.evulid.cc/js/evulid-matomo.js"></script><noscript><p><img src="https://mato.evulid.cc/matomo.php?idsite=8&amp;rec=1" style="border:0" alt="" /></p></noscript></head>
+<body>
+<h1>CSS selector-based cosmetic filters</h1>
+<p><a href="./.">Back</a>
+<br><br></p>
+<h3>Filters</h3>
+<div class="filters"><noscript>Enable JavaScript to see needed filters</noscript></div>
+
+<h3>Tests</h3>
+<div id="ccf" class="tests">
+
+<div id="a1" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code class="generic">#ccf #a1 .fail</code>
+    </div>
+
+<div id="a2" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code class="generic">#ccf #a2 .fail:not(.a2)</code>
+    </div>
+
+<div id="a3" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code>#ccf #a3 .fail</code>
+    </div>
+
+<div id="a4" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code>#ccf #a4 .fail:not(.a4)</code>
+    </div>
+
+<div id="a5" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code>#ccf #a5 .fail:style(visibility: hidden)</code>
+    </div>
+
+<div id="a6" class="tile">
+    <div class="pass"><div class="fail-pseudo"><a><b></b></a></div></div>
+    <code class="generic">#ccf #a6 .fail-pseudo::before</code>
+    </div>
+
+<div id="a7" class="tile">
+    <div class="pass"><div class="fail-pseudo"><a><b></b></a></div></div>
+    <code>#ccf #a7 .fail-pseudo::before</code>
+    </div>
+
+<div id="a8" class="tile">
+    <div class="pass"><div class="fail-pseudo"><a><b></b></a></div></div>
+    <code>#ccf #a8 .fail-pseudo::before:style(visibility: hidden)</code>
+    </div>
+
+</div>
+
+<script>
+    const hostname = self.location.hostname;
+    const filters = [];
+    const fragment = document.createDocumentFragment();
+    for ( const node of document.querySelectorAll('code') ) {
+        const div = document.createElement('div');
+        let text = '##' + node.textContent;
+        if ( node.classList.contains('generic') === false ) {
+            text = hostname + text;
+        }
+        div.textContent = text;
+        fragment.appendChild(div);
+    }
+    const parent = document.querySelector('.filters');
+    while ( parent.lastElementChild !== null ) {
+        parent.removeChild(parent.lastElementChild);
+    }
+    parent.appendChild(fragment);
+</script>
+</body>
+</html>
diff --git a/docs/tests/index.html b/docs/tests/index.html
index fec110a96..b0558c156 100644
--- a/docs/tests/index.html
+++ b/docs/tests/index.html
@@ -9,12 +9,14 @@
 <h1>uBlock Origin tests</h1>
 <p>Some of the pages below are hosted on <a href="raw.githack.com">raw.githack.com</a> in order to ensure some of the secondary resources can be properly loaded (specifically, the WebAssembly modules, as they <a href="https://github.com/WebAssembly/design/blob/master/Web.md#webassemblyinstantiatestreaming">require to be loaded using same-origin policy</a>).</p>
 <ul>
-<li><a href="https://raw.githack.com/gorhill/uBlock/master/docs/tests/hntrie-test.html">HNTrie: tests</a>
-<li><a href="https://raw.githack.com/gorhill/uBlock/master/docs/tests/hnset-benchmark.html">HNTrie, small (2) to medium (~1000) set: benchmarks</a>
-<li><a href="https://raw.githack.com/gorhill/uBlock/master/docs/tests/hnbigset-benchmark.html">HNTrie, small (2) to large (40,000+) set: benchmarks</a>
+<li><a href="css-selector-based-cosmetic-filters.html">CSS selector-based cosmetic filters</a>
 <li><a href="procedural-cosmetic-filters.html">Procedural cosmetic filters</a>
 <li><a href="procedural-html-filters.html">Procedural HTML filters</a>
 <li><a href="scriptlet-injection-filters-1.html">Scriptlet injection filters / no-setTimeout-if</a>
+<li>&nbsp;
+<li><a href="https://raw.githack.com/gorhill/uBlock/master/docs/tests/hntrie-test.html">HNTrie: tests</a>
+<li><a href="https://raw.githack.com/gorhill/uBlock/master/docs/tests/hnset-benchmark.html">HNTrie, small (2) to medium (~1000) set: benchmarks</a>
+<li><a href="https://raw.githack.com/gorhill/uBlock/master/docs/tests/hnbigset-benchmark.html">HNTrie, small (2) to large (40,000+) set: benchmarks</a>
 </ul>
 </body>
 </html>
diff --git a/docs/tests/procedural-cosmetic-filters.html b/docs/tests/procedural-cosmetic-filters.html
index 608d24986..714ea1acd 100644
--- a/docs/tests/procedural-cosmetic-filters.html
+++ b/docs/tests/procedural-cosmetic-filters.html
@@ -167,6 +167,21 @@
     <code>#pcf #a17 .fail:has(~ a:has(b))</code>
     </div>
 
+<div id="a18" class="tile">
+    <div class="pass"><div class="fail"></div><a><b></b></a></div>
+    <code>#pcf #a18 .fail:remove()</code>
+    </div>
+
+<div id="a19" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code>#pcf #a19 b:upward(2)</code>
+    </div>
+
+<div id="a20" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code>#pcf #a20 b:upward(.fail)</code>
+    </div>
+
 </div>
 
 <script>
diff --git a/docs/tests/procedural-html-filters.html b/docs/tests/procedural-html-filters.html
index 3108f52f3..23d7f017e 100644
--- a/docs/tests/procedural-html-filters.html
+++ b/docs/tests/procedural-html-filters.html
@@ -138,6 +138,16 @@
     <code>^#phf #a13 .fail:has(~ a:has(b))</code>
     </div>
 
+<div id="a14" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code>^#phf #a14 b:upward(2)</code>
+    </div>
+
+<div id="a15" class="tile">
+    <div class="pass"><div class="fail"><a><b></b></a></div></div>
+    <code>^#phf #a15 b:upward(.fail)</code>
+    </div>
+
 </div>
 
 <script>
diff --git a/platform/chromium/vapi-usercss.pseudo.js b/platform/chromium/vapi-usercss.pseudo.js
index 6d9f32e2d..dbf55b72f 100644
--- a/platform/chromium/vapi-usercss.pseudo.js
+++ b/platform/chromium/vapi-usercss.pseudo.js
@@ -184,7 +184,7 @@ vAPI.DOMFilterer = class {
                     Array.from(this.specificSimpleHide).join(',\n');
             }
             for ( const node of this.addedNodes ) {
-                if ( node[vAPI.matchesProp](this.specificSimpleHideAggregated) ) {
+                if ( node.matches(this.specificSimpleHideAggregated) ) {
                     this.hideNode(node);
                 }
                 const nodes = node.querySelectorAll(this.specificSimpleHideAggregated);
diff --git a/src/js/contentscript.js b/src/js/contentscript.js
index 779f1fc3d..cefa1930e 100644
--- a/src/js/contentscript.js
+++ b/src/js/contentscript.js
@@ -413,24 +413,6 @@ vAPI.domWatcher = (( ) => {
 /******************************************************************************/
 /******************************************************************************/
 
-vAPI.matchesProp = (( ) => {
-    const docElem = document.documentElement;
-    if ( typeof docElem.matches !== 'function' ) {
-        if ( typeof docElem.mozMatchesSelector === 'function' ) {
-            return 'mozMatchesSelector';
-        } else if ( typeof docElem.webkitMatchesSelector === 'function' ) {
-            return 'webkitMatchesSelector';
-        } else if ( typeof docElem.msMatchesSelector === 'function' ) {
-            return 'msMatchesSelector';
-        }
-    }
-    return 'matches';
-})();
-
-/******************************************************************************/
-/******************************************************************************/
-/******************************************************************************/
-
 vAPI.injectScriptlet = function(doc, text) {
     if ( !doc ) { return; }
     let script;
@@ -533,18 +515,10 @@ vAPI.DOMFilterer = (function() {
         }
     };
 
-    const PSelectorNthAncestorTask = class {
-        constructor(task) {
-            this.nth = task[1];
+    const PSelectorPassthru = class {
+        constructor() {
         }
         transpose(node, output) {
-            let nth = this.nth;
-            for (;;) {
-                node = node.parentElement;
-                if ( node === null ) { return; }
-                nth -= 1;
-                if ( nth === 0 ) { break; }
-            }
             output.push(node);
         }
     };
@@ -571,6 +545,36 @@ vAPI.DOMFilterer = (function() {
         }
     };
 
+    const PSelectorUpwardTask = class {
+        constructor(task) {
+            const arg = task[1];
+            if ( typeof arg === 'number' ) {
+                this.i = arg;
+            } else {
+                this.s = arg;
+            }
+        }
+        transpose(node, output) {
+            if ( this.s !== '' ) {
+                const parent = node.parentElement;
+                if ( parent === null ) { return; }
+                node = parent.closest(this.s);
+                if ( node === null ) { return; }
+            } else {
+                let nth = this.i;
+                for (;;) {
+                    node = node.parentElement;
+                    if ( node === null ) { return; }
+                    nth -= 1;
+                    if ( nth === 0 ) { break; }
+                }
+            }
+            output.push(node);
+        }
+    };
+    PSelectorUpwardTask.prototype.i = 0;
+    PSelectorUpwardTask.prototype.s = '';
+
     const PSelectorWatchAttrs = class {
         constructor(task) {
             this.observer = null;
@@ -637,8 +641,10 @@ vAPI.DOMFilterer = (function() {
                     [ ':matches-css-before', PSelectorMatchesCSSBeforeTask ],
                     [ ':min-text-length', PSelectorMinTextLengthTask ],
                     [ ':not', PSelectorIfNotTask ],
-                    [ ':nth-ancestor', PSelectorNthAncestorTask ],
+                    [ ':nth-ancestor', PSelectorUpwardTask ],
+                    [ ':remove', PSelectorPassthru ],
                     [ ':spath', PSelectorSpathTask ],
+                    [ ':upward', PSelectorUpwardTask ],
                     [ ':watch-attr', PSelectorWatchAttrs ],
                     [ ':xpath', PSelectorXpathTask ],
                 ]);
@@ -650,15 +656,21 @@ vAPI.DOMFilterer = (function() {
             this.selector = o.selector;
             this.tasks = [];
             const tasks = o.tasks;
-            if ( !tasks ) { return; }
-            for ( const task of tasks ) {
-                this.tasks.push(new (this.operatorToTaskMap.get(task[0]))(task));
+            if ( Array.isArray(tasks) ) {
+                for ( const task of tasks ) {
+                    this.tasks.push(
+                        new (this.operatorToTaskMap.get(task[0]))(task)
+                    );
+                }
+            }
+            if ( o.action !== undefined ) {
+                this.action = o.action;
             }
         }
         prime(input) {
             const root = input || document;
             if ( this.selector === '' ) { return [ root ]; }
-            return root.querySelectorAll(this.selector);
+            return Array.from(root.querySelectorAll(this.selector));
         }
         exec(input) {
             let nodes = this.prime(input);
@@ -689,6 +701,8 @@ vAPI.DOMFilterer = (function() {
             return false;
         }
     };
+    PSelector.prototype.action = undefined;
+    PSelector.prototype.hit = false;
     PSelector.prototype.operatorToTaskMap = undefined;
 
     const DOMProceduralFilterer = class {
@@ -707,20 +721,20 @@ vAPI.DOMFilterer = (function() {
             for ( let i = 0, n = aa.length; i < n; i++ ) {
                 const raw = aa[i];
                 const o = JSON.parse(raw);
-                if ( o.style ) {
-                    this.domFilterer.addCSSRule(o.style[0], o.style[1]);
+                if ( o.action === 'style' ) {
+                    this.domFilterer.addCSSRule(o.selector, o.tasks[0][1]);
                     mustCommit = true;
                     continue;
                 }
-                if ( o.pseudoclass ) {
+                if ( o.pseudo !== undefined ) {
                     this.domFilterer.addCSSRule(
-                        o.raw,
+                        o.selector,
                         'display:none!important;'
                     );
                     mustCommit = true;
                     continue;
                 }
-                if ( o.tasks ) {
+                if ( o.tasks !== undefined ) {
                     if ( this.selectors.has(raw) === false ) {
                         const pselector = new PSelector(o);
                         this.selectors.set(raw, pselector);
@@ -757,8 +771,7 @@ vAPI.DOMFilterer = (function() {
 
             let t0 = Date.now();
 
-            for ( const entry of this.selectors ) {
-                const pselector = entry[1];
+            for ( const pselector of this.selectors.values() ) {
                 const allowance = Math.floor((t0 - pselector.lastAllowanceTime) / 2000);
                 if ( allowance >= 1 ) {
                     pselector.budget += allowance * 50;
@@ -774,9 +787,12 @@ vAPI.DOMFilterer = (function() {
                     pselector.budget = -0x7FFFFFFF;
                 }
                 t0 = t1;
-                for ( const node of nodes ) {
-                    this.domFilterer.hideNode(node);
-                    this.hiddenNodes.add(node);
+                if ( nodes.length === 0 ) { continue; }
+                pselector.hit = true;
+                if ( pselector.action === 'remove' ) {
+                    this.removeNodes(nodes);
+                } else {
+                    this.hideNodes(nodes);
                 }
             }
 
@@ -787,6 +803,20 @@ vAPI.DOMFilterer = (function() {
             //console.timeEnd('procedural selectors/dom layout changed');
         }
 
+        hideNodes(nodes) {
+            for ( const node of nodes ) {
+                if ( node.parentElement === null ) { continue; }
+                this.domFilterer.hideNode(node);
+                this.hiddenNodes.add(node);
+            }
+        }
+
+        removeNodes(nodes) {
+            for ( const node of nodes ) {
+                node.remove();
+            }
+        }
+
         createProceduralFilter(o) {
             return new PSelector(o);
         }
diff --git a/src/js/cosmetic-filtering.js b/src/js/cosmetic-filtering.js
index 38fb1bdeb..66e240971 100644
--- a/src/js/cosmetic-filtering.js
+++ b/src/js/cosmetic-filtering.js
@@ -434,7 +434,7 @@ FilterContainer.prototype.compileGenericHideSelector = function(
     if (
         compiled === undefined ||
         compiled !== selector &&
-        µb.staticExtFilteringEngine.compileSelector.pseudoclass !== true
+        µb.staticExtFilteringEngine.compileSelector.pseudoclass === -1
     ) {
         if ( µb.hiddenSettings.allowGenericProceduralFilters === true ) {
             return this.compileSpecificSelector('', parsed, writer);
diff --git a/src/js/html-filtering.js b/src/js/html-filtering.js
index ba47229cd..e9e069827 100644
--- a/src/js/html-filtering.js
+++ b/src/js/html-filtering.js
@@ -95,22 +95,6 @@
         }
     };
 
-    const PSelectorNthAncestorTask = class {
-        constructor(task) {
-            this.nth = task[1];
-        }
-        transpose(node, output) {
-            let nth = this.nth;
-            for (;;) {
-                node = node.parentElement;
-                if ( node === null ) { return; }
-                nth -= 1;
-                if ( nth === 0 ) { break; }
-            }
-            output.push(node);
-        }
-    };
-
     const PSelectorSpathTask = class {
         constructor(task) {
             this.spath = task[1];
@@ -133,6 +117,36 @@
         }
     };
 
+    const PSelectorUpwardTask = class {
+        constructor(task) {
+            const arg = task[1];
+            if ( typeof arg === 'number' ) {
+                this.i = arg;
+            } else {
+                this.s = arg;
+            }
+        }
+        transpose(node, output) {
+            if ( this.s !== '' ) {
+                const parent = node.parentElement;
+                if ( parent === null ) { return; }
+                node = parent.closest(this.s);
+                if ( node === null ) { return; }
+            } else {
+                let nth = this.i;
+                for (;;) {
+                    node = node.parentElement;
+                    if ( node === null ) { return; }
+                    nth -= 1;
+                    if ( nth === 0 ) { break; }
+                }
+            }
+            output.push(node);
+        }
+    };
+    PSelectorUpwardTask.prototype.i = 0;
+    PSelectorUpwardTask.prototype.s = '';
+
     const PSelectorXpathTask = class {
         constructor(task) {
             this.xpe = task[1];
@@ -178,7 +192,7 @@
         prime(input) {
             const root = input || docRegister;
             if ( this.selector === '' ) { return [ root ]; }
-            return root.querySelectorAll(this.selector);
+            return Array.from(root.querySelectorAll(this.selector));
         }
         exec(input) {
             if ( this.invalid ) { return []; }
@@ -218,8 +232,9 @@
         [ ':if-not', PSelectorIfNotTask ],
         [ ':min-text-length', PSelectorMinTextLengthTask ],
         [ ':not', PSelectorIfNotTask ],
-        [ ':nth-ancestor', PSelectorNthAncestorTask ],
+        [ ':nth-ancestor', PSelectorUpwardTask ],
         [ ':spath', PSelectorSpathTask ],
+        [ ':upward', PSelectorUpwardTask ],
         [ ':xpath', PSelectorXpathTask ],
     ]);
     PSelector.prototype.invalid = false;
@@ -246,14 +261,10 @@
             pselectors.set(selector, pselector);
         }
         const nodes = pselector.exec();
-        let i = nodes.length,
-            modified = false;
-        while ( i-- ) {
-            const node = nodes[i];
-            if ( node.parentNode !== null ) {
-                node.parentNode.removeChild(node);
-                modified = true;
-            }
+        let modified = false;
+        for ( const node of nodes ) {
+            node.remove();
+            modified = true;
         }
         if ( modified && µb.logger.enabled ) {
             logOne(details, 0, pselector.raw);
@@ -263,14 +274,10 @@
 
     const applyCSSSelector = function(details, selector) {
         const nodes = docRegister.querySelectorAll(selector);
-        let i = nodes.length,
-            modified = false;
-        while ( i-- ) {
-            const node = nodes[i];
-            if ( node.parentNode !== null ) {
-                node.parentNode.removeChild(node);
-                modified = true;
-            }
+        let modified = false;
+        for ( const node of nodes ) {
+            node.remove();
+            modified = true;
         }
         if ( modified && µb.logger.enabled ) {
             logOne(details, 0, selector);
diff --git a/src/js/scriptlets/cosmetic-logger.js b/src/js/scriptlets/cosmetic-logger.js
index e8be4fc4a..a7c6aef3e 100644
--- a/src/js/scriptlets/cosmetic-logger.js
+++ b/src/js/scriptlets/cosmetic-logger.js
@@ -147,10 +147,10 @@ const processDeclarativeStyle = function(out) {
 
 const processProcedural = function(out) {
     if ( proceduralDict.size === 0 ) { return; }
-    for ( const entry of proceduralDict ) {
-        if ( entry[1].test() === false ) { continue; }
-        out.push(`##${entry[1].raw}`);
-        proceduralDict.delete(entry[0]);
+    for ( const [ raw, pselector ] of proceduralDict ) {
+        if ( pselector.hit === false ) { continue; }
+        out.push(`##${raw}`);
+        proceduralDict.delete(raw);
     }
 };
 
diff --git a/src/js/scriptlets/element-picker.js b/src/js/scriptlets/element-picker.js
index 7ba5e2412..71daae40f 100644
--- a/src/js/scriptlets/element-picker.js
+++ b/src/js/scriptlets/element-picker.js
@@ -822,11 +822,11 @@ const filterToDOMInterface = (( ) => {
         let elems;
         try {
             const o = JSON.parse(raw);
-            if ( o.style ) {
+            if ( o.action === 'style' ) {
                 elems = document.querySelectorAll(
-                    o.style[0].replace(rePseudoElements, '')
+                    o.selector.replace(rePseudoElements, '')
                 );
-                lastAction = o.style[0] + ' {' + o.style[1] + '}';
+                lastAction = o.selector + ' {' + o.tasks[0][1] + '}';
             } else if ( o.tasks ) {
                 elems = vAPI.domFilterer.createProceduralFilter(o).exec();
             }
diff --git a/src/js/static-ext-filtering.js b/src/js/static-ext-filtering.js
index 1b0be8901..2de1e29f0 100644
--- a/src/js/static-ext-filtering.js
+++ b/src/js/static-ext-filtering.js
@@ -68,46 +68,52 @@
         parsed.suffix = '';
     };
 
-    const isValidCSSSelector = (( ) => {
+    const cssPseudoSelector = (( ) => {
+        const rePseudo = /:(?::?after|:?before|:[a-z][a-z-]*[a-z])$/;
+        return function(s) {
+            if ( s.lastIndexOf(':') === -1 ) { return -1; }
+            const match = rePseudo.exec(s);
+            return match !== null ? match.index : -1;
+        };
+    })();
+
+    // Return value:
+    //   0b00 (0) = not a valid CSS selector
+    //   0b01 (1) = valid CSS selector, without pseudo-element
+    //   0b11 (3) = valid CSS selector, with pseudo element
+    const cssSelectorType = (( ) => {
         const div = document.createElement('div');
-        let matchesFn;
         // Keep in mind:
         //   https://github.com/gorhill/uBlock/issues/693
         //   https://github.com/gorhill/uBlock/issues/1955
-        if ( div.matches instanceof Function ) {
-            matchesFn = div.matches.bind(div);
-        } else if ( div.mozMatchesSelector instanceof Function ) {
-            matchesFn = div.mozMatchesSelector.bind(div);
-        } else if ( div.webkitMatchesSelector instanceof Function ) {
-            matchesFn = div.webkitMatchesSelector.bind(div);
-        } else if ( div.msMatchesSelector instanceof Function ) {
-            matchesFn = div.msMatchesSelector.bind(div);
-        } else {
-            matchesFn = div.querySelector.bind(div);
-        }
         // https://github.com/gorhill/uBlock/issues/3111
         //   Workaround until https://bugzilla.mozilla.org/show_bug.cgi?id=1406817
         //   is fixed.
+        let matchFn; 
         try {
-            matchesFn(':scope');
+            div.matches(':scope');
+            matchFn = div.matches.bind(div); 
         } catch (ex) {
-            matchesFn = div.querySelector.bind(div);
+            matchFn = div.querySelector.bind(div);
         }
         // Quick regex-based validation -- most cosmetic filters are of the
         // simple form and in such case a regex is much faster.
         const reSimple = /^[#.][\w-]+$/;
         return s => {
-            if ( reSimple.test(s) ) { return true; }
-            try {
-                matchesFn(`${s}, ${s}:not(#foo)`);
-            } catch (ex) {
-                return false;
+            if ( reSimple.test(s) ) { return 1; }
+            const pos = cssPseudoSelector(s);
+            if ( pos !== -1 ) {
+                return cssSelectorType(s.slice(0, pos)) === 1 ? 3 : 0;
             }
-            return true;
+            try {
+                matchFn(`${s}, ${s}:not(#foo)`);
+            } catch (ex) {
+                return 0;
+            }
+            return 1;
         };
     })();
 
-
     const isBadRegex = function(s) {
         try {
             void new RegExp(s);
@@ -123,12 +129,17 @@
         if ( matches === null ) { return ''; }
         const selector = matches[1].trim();
         const style = matches[2].trim();
+        // Special style directive `remove: true` is converted into a
+        // `:remove()` operator.
+        if ( /^\s*remove:\s*true[; ]*$/.test(style) ) {
+            return `${selector}:remove()`;
+        }
         // For some reasons, many of Adguard's plain cosmetic filters are
         // "disguised" as style-based cosmetic filters: convert such filters
         // to plain cosmetic filters.
         return /display\s*:\s*none\s*!important;?$/.test(style)
             ? selector
-            : selector + ':style(' +  style + ')';
+            : `${selector}:style(${style})`;
     };
 
     const hostnamesFromPrefix = function(s) {
@@ -169,6 +180,9 @@
                 'min-text-length',
                 'not',
                 'nth-ancestor',
+                'remove',
+                'style',
+                'upward',
                 'watch-attr',
                 'watch-attrs',
                 'xpath'
@@ -237,9 +251,8 @@
         const compileInteger = function(s, min = 0, max = 0x7FFFFFFF) {
             if ( /^\d+$/.test(s) === false ) { return; }
             const n = parseInt(s, 10);
-            if ( n >= min && n < max ) {
-                return n;
-            }
+            if ( n < min || n >= max ) { return; }
+            return n;
         };
 
         const compileNotSelector = function(s) {
@@ -247,21 +260,42 @@
             //   Reject instances of :not() filters for which the argument is
             //   a valid CSS selector, otherwise we would be adversely
             //   changing the behavior of CSS4's :not().
-            if ( isValidCSSSelector(s) === false ) {
+            if ( cssSelectorType(s) === 0 ) {
                 return compileConditionalSelector(s);
             }
         };
 
-        const compileNthAncestorSelector = function(s) {
-            return compileInteger(s, 1, 256);
+        const compileUpwardArgument = function(s) {
+            const i = compileInteger(s, 1, 256);
+            if ( i !== undefined ) { return i; }
+            if ( cssSelectorType(s) === 1 ) { return s; }
+        };
+
+        const compileRemoveSelector = function(s) {
+            if ( s === '' ) { return s; }
         };
 
         const compileSpathExpression = function(s) {
-            if ( isValidCSSSelector('*' + s) ) {
+            if ( cssSelectorType('*' + s) === 1 ) {
                 return s;
             }
         };
 
+        const compileStyleProperties = (( ) => {
+            let div;
+            // https://github.com/uBlockOrigin/uBlock-issues/issues/668
+            return function(s) {
+                if ( /url\(|\\/i.test(s) ) { return; }
+                if ( div === undefined ) {
+                    div = document.createElement('div');
+                }
+                div.style.cssText = s;
+                if ( div.style.cssText === '' ) { return; }
+                div.style.cssText = '';
+                return s;
+            };
+        })();
+
         const compileAttrList = function(s) {
             const attrs = s.split('\s*,\s*');
             const out = [];
@@ -287,6 +321,7 @@
             [ ':-abp-contains', ':has-text' ],
             [ ':-abp-has', ':has' ],
             [ ':contains', ':has-text' ],
+            [ ':nth-ancestor', ':upward' ],
             [ ':watch-attrs', ':watch-attr' ],
         ]);
 
@@ -300,12 +335,19 @@
             [ ':matches-css-before', compileCSSDeclaration ],
             [ ':min-text-length', compileInteger ],
             [ ':not', compileNotSelector ],
-            [ ':nth-ancestor', compileNthAncestorSelector ],
+            [ ':remove', compileRemoveSelector ],
             [ ':spath', compileSpathExpression ],
+            [ ':style', compileStyleProperties ],
+            [ ':upward', compileUpwardArgument ],
             [ ':watch-attr', compileAttrList ],
             [ ':xpath', compileXpathExpression ],
         ]);
 
+        const actionOperators = new Set([
+            ':remove',
+            ':style',
+        ]);
+
         // https://github.com/gorhill/uBlock/issues/2793#issuecomment-333269387
         //   Normalize (somewhat) the stringified version of procedural
         //   cosmetic filters -- this increase the likelihood of detecting
@@ -358,7 +400,9 @@
                     raw.push(task[1]);
                     break;
                 case ':min-text-length':
-                case ':nth-ancestor':
+                case ':remove':
+                case ':style':
+                case ':upward':
                 case ':watch-attr':
                 case ':xpath':
                     raw.push(`${task[0]}(${task[1]})`);
@@ -370,11 +414,14 @@
 
         const compile = function(raw, root = false) {
             if ( raw === '' ) { return; }
-            let prefix = '',
-                tasks = [];
-            let i = 0,
-                n = raw.length,
-                opPrefixBeg = 0;
+
+            const tasks = [];
+            const n = raw.length;
+            let prefix = '';
+            let i = 0;
+            let opPrefixBeg = 0;
+            let action;
+
             for (;;) {
                 let c, match;
                 // Advance to next operator.
@@ -410,45 +457,58 @@
                 if ( pcnt !== 0 && c !== 0x29 ) { return; }
                 // https://github.com/uBlockOrigin/uBlock-issues/issues/341#issuecomment-447603588
                 //   Maybe that one operator is a valid CSS selector and if so,
-                //   then consider it to be part of the prefix. If there is
-                //   at least one task present, then we fail, as we do not
-                //   support suffix CSS selectors.
-                if ( isValidCSSSelector(raw.slice(opNameBeg, i)) ) { continue; }
+                //   then consider it to be part of the prefix.
+                if ( cssSelectorType(raw.slice(opNameBeg, i)) === 1 ) {
+                    continue;
+                }
                 // Extract and remember operator details.
                 let operator = raw.slice(opNameBeg, opNameEnd);
                 operator = normalizedOperators.get(operator) || operator;
-                let args = raw.slice(opNameEnd + 1, i - 1);
-                args = compileArgument.get(operator)(args);
+                // Action operator can only be used as trailing operator in the
+                // root task list.
+                // Per-operator arguments validation
+                const args = compileArgument.get(operator)(
+                    raw.slice(opNameEnd + 1, i - 1)
+                );
                 if ( args === undefined ) { return; }
                 if ( opPrefixBeg === 0 ) {
                     prefix = raw.slice(0, opNameBeg);
                 } else if ( opNameBeg !== opPrefixBeg ) {
+                    if ( action !== undefined ) { return; }
                     const spath = compileSpathExpression(
                         raw.slice(opPrefixBeg, opNameBeg)
                     );
                     if ( spath === undefined ) { return; }
                     tasks.push([ ':spath', spath ]);
                 }
+                if ( action !== undefined ) { return; }
                 tasks.push([ operator, args ]);
+                if ( actionOperators.has(operator) ) {
+                    if ( root === false ) { return; }
+                    action = operator.slice(1);
+                }
                 opPrefixBeg = i;
                 if ( i === n ) { break; }
             }
+
             // No task found: then we have a CSS selector.
             // At least one task found: nothing should be left to parse.
             if ( tasks.length === 0 ) {
                 prefix = raw;
             } else if ( opPrefixBeg < n ) {
+                if ( action !== undefined ) { return; }
                 const spath = compileSpathExpression(raw.slice(opPrefixBeg));
                 if ( spath === undefined ) { return; }
                 tasks.push([ ':spath', spath ]);
             }
+
             // https://github.com/NanoAdblocker/NanoCore/issues/1#issuecomment-354394894
             // https://www.reddit.com/r/uBlockOrigin/comments/c6iem5/
             //   Convert sibling-selector prefix into :spath operator, but
             //   only if context is not the root.
             if ( prefix !== '' ) {
                 if ( reIsDanglingSelector.test(prefix) ) { prefix += '*'; }
-                if ( isValidCSSSelector(prefix) === false ) {
+                if ( cssSelectorType(prefix) === 0 ) {
                     if (
                         root ||
                         reIsSiblingSelector.test(prefix) === false ||
@@ -460,10 +520,28 @@
                     prefix = '';
                 }
             }
-            if ( tasks.length === 0 ) {
-                tasks = undefined;
+
+            const out = { selector: prefix };
+
+            if ( tasks.length !== 0 ) {
+                out.tasks = tasks;
             }
-            return { selector: prefix, tasks: tasks };
+
+            // Expose action to take in root descriptor.
+            if ( action !== undefined ) {
+                out.action = action;
+            }
+
+            // Pseudo-selectors are valid only when used in a root task list.
+            if ( prefix !== '' ) {
+                const pos = cssPseudoSelector(prefix);
+                if ( pos !== -1 ) {
+                    if ( root === false ) { return; }
+                    out.pseudo = pos;
+                }
+            }
+
+            return out;
         };
 
         const entryPoint = function(raw) {
@@ -474,7 +552,6 @@
             let compiled = compile(raw, true);
             if ( compiled !== undefined ) {
                 compiled.raw = decompile(compiled);
-                compiled = JSON.stringify(compiled);
             }
             lastProceduralSelectorCompiled = compiled;
             return compiled;
@@ -704,11 +781,8 @@
     //   Do not discard unknown pseudo-elements.
 
     api.compileSelector = (( ) => {
-        const reAfterBeforeSelector = /^(.+?)(::?after|::?before|::[a-z-]+)$/;
-        const reStyleSelector = /^(.+?):style\((.+?)\)$/;
         const reExtendedSyntax = /\[-(?:abp|ext)-[a-z-]+=(['"])(?:.+?)(?:\1)\]/;
         const reExtendedSyntaxParser = /\[-(?:abp|ext)-([a-z-]+)=(['"])(.+?)\2\]/;
-        const div = document.createElement('div');
 
         const normalizedExtendedSyntaxOperators = new Map([
             [ 'contains', ':has-text' ],
@@ -718,29 +792,17 @@
             [ 'matches-css-before', ':matches-css-before' ],
         ]);
 
-        const isValidStyleProperty = function(cssText) {
-            if ( reStyleBad.test(cssText) ) { return false; }
-            div.style.cssText = cssText;
-            if ( div.style.cssText === '' ) { return false; }
-            div.style.cssText = '';
-            return true;
-        };
-        // https://github.com/uBlockOrigin/uBlock-issues/issues/668
-        const reStyleBad = /url\(|\\/i;
-
         const entryPoint = function(raw) {
-            entryPoint.pseudoclass = false;
+            entryPoint.pseudoclass = -1;
 
             const extendedSyntax = reExtendedSyntax.test(raw);
-            if ( isValidCSSSelector(raw) && extendedSyntax === false ) {
+            if ( cssSelectorType(raw) === 1 && extendedSyntax === false ) {
                 return raw;
             }
 
             // We  rarely reach this point -- majority of selectors are plain
             // CSS selectors.
 
-            let matches;
-
             // Supported Adguard/ABP advanced selector syntax: will translate
             // into uBO's syntax before further processing.
             // Mind unsupported advanced selector syntax, such as ABP's
@@ -749,6 +811,7 @@
             // favor of the procedural one (i.e. `:operator(...)`).
             // See https://issues.adblockplus.org/ticket/5287
             if ( extendedSyntax ) {
+                let matches;
                 while ( (matches = reExtendedSyntaxParser.exec(raw)) !== null ) {
                     const operator = normalizedExtendedSyntaxOperators.get(matches[1]);
                     if ( operator === undefined ) { return; }
@@ -759,42 +822,18 @@
                 return entryPoint(raw);
             }
 
-            let selector = raw, pseudoclass, style;
-
-            // `:style` selector?
-            if ( (matches = reStyleSelector.exec(selector)) !== null ) {
-                selector = matches[1];
-                style = matches[2];
-            }
-
-            // https://github.com/gorhill/uBlock/issues/2448
-            // :after- or :before-based selector?
-            if ( (matches = reAfterBeforeSelector.exec(selector)) ) {
-                selector = matches[1];
-                pseudoclass = matches[2];
-            }
-
-            if ( style !== undefined || pseudoclass !== undefined ) {
-                if ( isValidCSSSelector(selector) === false ) { return; }
-                if ( pseudoclass !== undefined ) {
-                    selector += pseudoclass;
-                }
-                if ( style !== undefined ) {
-                    if ( isValidStyleProperty(style) === false ) { return; }
-                    return JSON.stringify({ raw, style: [ selector, style ] });
-                }
-                entryPoint.pseudoclass = true;
-                return JSON.stringify({ raw, pseudoclass: true });
-            }
-
             // Procedural selector?
             const compiled = compileProceduralSelector(raw);
-            if ( compiled !== undefined ) {
-                return compiled;
+            if ( compiled === undefined ) { return; }
+
+            if ( compiled.pseudo !== undefined ) {
+                entryPoint.pseudoclass = compiled.pseudo;
             }
+
+            return JSON.stringify(compiled);
         };
 
-        entryPoint.pseudoclass = false;
+        entryPoint.pseudoclass = -1;
 
         return entryPoint;
     })();
