diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
index 7af45ca96..8a9c3d843 100644
--- a/.github/PULL_REQUEST_TEMPLATE.md
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -22,10 +22,6 @@ merge of your pull request!
 
 **Why**:
 
-<!-- How were these changes implemented? -->
-
-**How**:
-
 <!-- Have you done all of these things?  -->
 
 **Checklist**:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0cb5e9173..552458ef6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,7 @@ on:
 
 jobs:
   node_tests:
-    name: 'Test stylus on ${{matrix.os}} with node16'
+    name: 'Test stylus on ${{matrix.os}} with node18'
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
@@ -22,7 +22,7 @@ jobs:
      - uses: actions/setup-node@v3
        with:
          # The Node.js version to configure
-         node-version: '16'
+         node-version: '18'
      - name: Install npm dependencies
        run: npm install
      - name: Print node & npm version
@@ -36,7 +36,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        node: [10, 12, 14, 18]
+        node: [10, 12, 14, 16, 20]
     runs-on: ${{ matrix.os }}
     steps:
      - uses: actions/checkout@v3
@@ -96,3 +96,23 @@ jobs:
        run: npm install
      - name: Run nyc
        run: npx nyc@latest npm run test
+
+  deno_tests:
+    name: 'Test stylus on ${{matrix.os}} with latest stable deno'
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+     # Pull repo to test machine
+     - uses: actions/checkout@v3
+     # Configures the deno version used on GitHub-hosted runners
+     - uses: denoland/setup-deno@v1
+       with:
+         # Run with latest stable Deno
+         deno-version: v1.x
+     - name: Print deno version
+       # Output useful info for debugging.
+       run: deno --version
+     - name: Run Test
+       run: deno run -A deno/test.ts
diff --git a/deno/test.ts b/deno/test.ts
new file mode 100644
index 000000000..0156bf0ed
--- /dev/null
+++ b/deno/test.ts
@@ -0,0 +1,33 @@
+import Mocha from "mocha";
+
+import fs from "node:fs";
+import path from "node:path";
+import process from "node:process";
+
+globalThis.process = process;
+
+const mocha = new Mocha({
+  bail: true,
+  checkLeaks: true,
+  require: ["chai"],
+  reporter: "dot",
+});
+
+const testDirs = ["test/", "test/middleware/"];
+
+testDirs.forEach((testDir) => {
+  fs
+    .readdirSync(testDir)
+    .filter(function (file) {
+      if (testDir === "test/" && file === "deno.js") return false;
+
+      return file.slice(-3) === ".js";
+    })
+    .forEach(function (file) {
+      mocha.addFile(path.join(testDir, file));
+    });
+});
+
+mocha.run(function (failures) {
+  process.exitCode = failures ? 1 : 0;
+});
diff --git a/docs/docs/js.md b/docs/docs/js.md
index 28297aac7..37b0f92f1 100644
--- a/docs/docs/js.md
+++ b/docs/docs/js.md
@@ -66,7 +66,7 @@ stylus(str)
 });
 ```
 
-## .define(name, node)
+## .define(name, node[, raw])
 
 By passing a `Node`, we may define a global variable. This is useful when exposing conditional features within your library depending on the availability of another. For example the **Nib** extension library conditionally supports node-canvas, providing image generation. 
  
@@ -89,6 +89,8 @@ Stylus also casts JavaScript values to their Stylus equivalents when possible. H
 .define('families', ['Helvetica Neue', 'Helvetica', 'sans-serif'])
 ```
 
+Note: In default, The JavaScript object variable will coerce to a tuple-array-like expression. For example `{ foo: 'bar', bar: 'baz' }` would become the expression `(foo 'bar') (bar 'baz')`. If you want to get a [hash object](https://stylus-lang.com/docs/hashes.html) return, please set `raw` to `true`.
+
 These same rules apply to return values in js functions as well:
 
 ```js
diff --git a/docs/index.md b/docs/index.md
index f36c944b5..e7f62695b 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -3,12 +3,12 @@ layout: home
 sidebar: false
 
 title: Stylus
-titleTemplate: An expressive, robust, feature-rich CSS language built for nodejs
+titleTemplate: An expressive, robust, feature-rich CSS language built for Node.js
 
 hero:
   name: Stylus
-  text: Expressive, dynamic and robust CSSs
-  tagline: An expressive, robust, feature-rich CSS language built for nodejs
+  text: Expressive, dynamic, and robust CSS
+  tagline: An expressive, robust, feature-rich CSS language built for Node.js
   image:
     src: /logo.svg
     alt: Stylus
@@ -27,12 +27,12 @@ hero:
       link: https://github.com/stylus/stylus
 
 features:
-  - title: Born for Nodejs
-    details: TJ create this project for nodejs ecosystem since 2010
+  - title: Born for Node.js
+    details: TJ created this project for the Node.js Ecosystem in 2010
   - title: CSS Compatible
-    details: Don't like indented syntax ? ok, it's optional! You can write stylus like css-style without pain
+    details: Don't like indented syntax? OK, it's optional! You can write Stylus like CSS without the pain
   - title: IDE support
-    details: Both VSCode (with stylus extension) and WebStorm (builtin) support stylus development
+    details: Both VSCode (with Stylus extension) and WebStorm (built in) support Stylus development
   - title: All optional
-    details: braces, semi-colons and more can be omit in your code, keep clean and less
+    details: Braces, semi-colons, and more can be omitted from your code to keep it clean and smaller
 ---
diff --git a/docs/package-lock.json b/docs/package-lock.json
index 83469b4d1..0514a0ba1 100644
--- a/docs/package-lock.json
+++ b/docs/package-lock.json
@@ -2200,6 +2200,15 @@
       "integrity": "sha512-zhaCDicdLuWN5UbN5IMnFqNMhNfo919sH85y2/ea+5Yg9TsTkeZxpL+JLbp6cgYFS4sRLp3YV4S6yDuqVWHYOw==",
       "dev": true
     },
+    "busboy": {
+      "version": "1.6.0",
+      "resolved": "https://registry.npmjs.org/busboy/-/busboy-1.6.0.tgz",
+      "integrity": "sha512-8SFQbg/0hQ9xy3UNTB0YEnsNBbWfhf7RtnzpL7TkBiTBRfrQ9Fxcnz7VJsleJpyp6rVLvXiuORqjlHi5q+PYuA==",
+      "dev": true,
+      "requires": {
+        "streamsearch": "^1.1.0"
+      }
+    },
     "bytes": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/bytes/-/bytes-3.0.0.tgz",
@@ -3572,9 +3581,9 @@
       "dev": true
     },
     "json5": {
-      "version": "2.2.1",
-      "resolved": "https://registry.npmjs.org/json5/-/json5-2.2.1.tgz",
-      "integrity": "sha512-1hqLFMSrGHRHxav9q9gNjJ5EXznIxGVO09xQRrwplcS8qs28pZ8s8hupZAmqDwZUmVZ2Qb2jnyPOWcDH8m8dlA==",
+      "version": "2.2.3",
+      "resolved": "https://registry.npmjs.org/json5/-/json5-2.2.3.tgz",
+      "integrity": "sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg==",
       "dev": true
     },
     "jsonc-parser": {
@@ -4419,6 +4428,12 @@
       "integrity": "sha512-RwNA9Z/7PrK06rYLIzFMlaF+l73iwpzsqRIFgbMLbTcLD6cOao82TaWefPXQvB2fOC4AjuYSEndS7N/mTCbkdQ==",
       "dev": true
     },
+    "streamsearch": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/streamsearch/-/streamsearch-1.1.0.tgz",
+      "integrity": "sha512-Mcc5wHehp9aXz1ax6bZUyY5afg9u2rv5cqQI3mRrYkGC8rW2hM02jWuwjtL++LS5qinSyhj2QfLyNsuc+VsExg==",
+      "dev": true
+    },
     "string.prototype.matchall": {
       "version": "4.0.7",
       "resolved": "https://registry.npmjs.org/string.prototype.matchall/-/string.prototype.matchall-4.0.7.tgz",
@@ -4634,10 +4649,13 @@
       }
     },
     "undici": {
-      "version": "5.10.0",
-      "resolved": "https://registry.npmjs.org/undici/-/undici-5.10.0.tgz",
-      "integrity": "sha512-c8HsD3IbwmjjbLvoZuRI26TZic+TSEe8FPMLLOkN1AfYRhdjnKBU6yL+IwcSCbdZiX4e5t0lfMDLDCqj4Sq70g==",
-      "dev": true
+      "version": "5.19.1",
+      "resolved": "https://registry.npmjs.org/undici/-/undici-5.19.1.tgz",
+      "integrity": "sha512-YiZ61LPIgY73E7syxCDxxa3LV2yl3sN8spnIuTct60boiiRaE1J8mNWHO8Im2Zi/sFrPusjLlmRPrsyraSqX6A==",
+      "dev": true,
+      "requires": {
+        "busboy": "^1.6.0"
+      }
     },
     "unicode-canonical-property-names-ecmascript": {
       "version": "2.0.0",
@@ -4800,9 +4818,9 @@
       "dev": true
     },
     "vite": {
-      "version": "2.9.15",
-      "resolved": "https://registry.npmjs.org/vite/-/vite-2.9.15.tgz",
-      "integrity": "sha512-fzMt2jK4vQ3yK56te3Kqpkaeq9DkcZfBbzHwYpobasvgYmP2SoAr6Aic05CsB4CzCZbsDv4sujX3pkEGhLabVQ==",
+      "version": "2.9.16",
+      "resolved": "https://registry.npmjs.org/vite/-/vite-2.9.16.tgz",
+      "integrity": "sha512-X+6q8KPyeuBvTQV8AVSnKDvXoBMnTx8zxh54sOwmmuOdxkjMmEJXH2UEchA+vTMps1xw9vL64uwJOWryULg7nA==",
       "dev": true,
       "requires": {
         "esbuild": "^0.14.27",
diff --git a/lib/errors.js b/lib/errors.js
index 7fa9a3506..5f8c5aa54 100644
--- a/lib/errors.js
+++ b/lib/errors.js
@@ -31,7 +31,7 @@ function ParseError(msg) {
  * Inherit from `Error.prototype`.
  */
 
-ParseError.prototype.__proto__ = Error.prototype;
+Object.setPrototypeOf(ParseError.prototype, Error.prototype);
 
 /**
  * Initialize a new `SyntaxError` with the given `msg`.
@@ -52,4 +52,4 @@ function SyntaxError(msg) {
  * Inherit from `Error.prototype`.
  */
 
-SyntaxError.prototype.__proto__ = Error.prototype;
+Object.setPrototypeOf(SyntaxError.prototype, Error.prototype);
diff --git a/lib/nodes/arguments.js b/lib/nodes/arguments.js
index c774a6fe4..757b6bfc6 100644
--- a/lib/nodes/arguments.js
+++ b/lib/nodes/arguments.js
@@ -26,7 +26,7 @@ var Arguments = module.exports = function Arguments(){
  * Inherit from `nodes.Expression.prototype`.
  */
 
-Arguments.prototype.__proto__ = nodes.Expression.prototype;
+Object.setPrototypeOf(Arguments.prototype, nodes.Expression.prototype);
 
 /**
  * Initialize an `Arguments` object with the nodes
diff --git a/lib/nodes/atblock.js b/lib/nodes/atblock.js
index 03a191cf2..07a6406b1 100644
--- a/lib/nodes/atblock.js
+++ b/lib/nodes/atblock.js
@@ -32,7 +32,7 @@ Atblock.prototype.__defineGetter__('nodes', function(){
  * Inherit from `Node.prototype`.
  */
 
-Atblock.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Atblock.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
diff --git a/lib/nodes/atrule.js b/lib/nodes/atrule.js
index 43301b500..d51e86f41 100644
--- a/lib/nodes/atrule.js
+++ b/lib/nodes/atrule.js
@@ -26,7 +26,7 @@ var Atrule = module.exports = function Atrule(type){
  * Inherit from `Node.prototype`.
  */
 
-Atrule.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Atrule.prototype, Node.prototype);
 
 /**
  * Check if at-rule's block has only properties.
diff --git a/lib/nodes/binop.js b/lib/nodes/binop.js
index c56aee398..e61343f53 100644
--- a/lib/nodes/binop.js
+++ b/lib/nodes/binop.js
@@ -31,11 +31,11 @@ var BinOp = module.exports = function BinOp(op, left, right){
  * Inherit from `Node.prototype`.
  */
 
-BinOp.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(BinOp.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/block.js b/lib/nodes/block.js
index b80af817b..766999c37 100644
--- a/lib/nodes/block.js
+++ b/lib/nodes/block.js
@@ -30,7 +30,7 @@ var Block = module.exports = function Block(parent, node){
  * Inherit from `Node.prototype`.
  */
 
-Block.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Block.prototype, Node.prototype);
 
 /**
  * Check if this block has properties..
@@ -77,7 +77,7 @@ Block.prototype.__defineGetter__('isEmpty', function(){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/boolean.js b/lib/nodes/boolean.js
index 97c11971b..dfd691ac6 100644
--- a/lib/nodes/boolean.js
+++ b/lib/nodes/boolean.js
@@ -24,7 +24,7 @@ var Boolean = module.exports = function Boolean(val){
   if (this.nodeName) {
     this.val = !!val;
   } else {
-    return new Boolean(val);
+    return new Boolean(!!val);
   }
 };
 
@@ -32,7 +32,7 @@ var Boolean = module.exports = function Boolean(val){
  * Inherit from `Node.prototype`.
  */
 
-Boolean.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Boolean.prototype, Node.prototype);
 
 /**
  * Return `this` node.
diff --git a/lib/nodes/call.js b/lib/nodes/call.js
index 5cf655df3..5b9e7a05f 100644
--- a/lib/nodes/call.js
+++ b/lib/nodes/call.js
@@ -29,11 +29,11 @@ var Call = module.exports = function Call(name, args){
  * Inherit from `Node.prototype`.
  */
 
-Call.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Call.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/charset.js b/lib/nodes/charset.js
index e6d520771..86b4b2511 100644
--- a/lib/nodes/charset.js
+++ b/lib/nodes/charset.js
@@ -27,7 +27,7 @@ var Charset = module.exports = function Charset(val){
  * Inherit from `Node.prototype`.
  */
 
-Charset.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Charset.prototype, Node.prototype);
 
 /**
  * Return @charset "val".
diff --git a/lib/nodes/comment.js b/lib/nodes/comment.js
index 56b59b3bf..520a2ca47 100644
--- a/lib/nodes/comment.js
+++ b/lib/nodes/comment.js
@@ -31,7 +31,7 @@ var Comment = module.exports = function Comment(str, suppress, inline){
  * Inherit from `Node.prototype`.
  */
 
-Comment.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Comment.prototype, Node.prototype);
 
 /**
  * Return a JSON representation of this node.
diff --git a/lib/nodes/each.js b/lib/nodes/each.js
index 985bd29da..2c8e5c02d 100644
--- a/lib/nodes/each.js
+++ b/lib/nodes/each.js
@@ -35,11 +35,11 @@ var Each = module.exports = function Each(val, key, expr, block){
  * Inherit from `Node.prototype`.
  */
 
-Each.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Each.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/expression.js b/lib/nodes/expression.js
index 92293f32f..fa4cac68d 100644
--- a/lib/nodes/expression.js
+++ b/lib/nodes/expression.js
@@ -67,11 +67,11 @@ Expression.prototype.__defineGetter__('hash', function(){
  * Inherit from `Node.prototype`.
  */
 
-Expression.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Expression.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/extend.js b/lib/nodes/extend.js
index 05458b612..52c2f5a47 100644
--- a/lib/nodes/extend.js
+++ b/lib/nodes/extend.js
@@ -27,11 +27,11 @@ var Extend = module.exports = function Extend(selectors){
  * Inherit from `Node.prototype`.
  */
 
-Extend.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Extend.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/feature.js b/lib/nodes/feature.js
index f4e183282..d15ac59e5 100644
--- a/lib/nodes/feature.js
+++ b/lib/nodes/feature.js
@@ -28,11 +28,11 @@ var Feature = module.exports = function Feature(segs){
  * Inherit from `Node.prototype`.
  */
 
-Feature.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Feature.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/function.js b/lib/nodes/function.js
index 25a6586bc..f5149587c 100644
--- a/lib/nodes/function.js
+++ b/lib/nodes/function.js
@@ -43,7 +43,7 @@ Function.prototype.__defineGetter__('arity', function(){
  * Inherit from `Node.prototype`.
  */
 
-Function.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Function.prototype, Node.prototype);
 
 /**
  * Return hash.
@@ -58,7 +58,7 @@ Function.prototype.__defineGetter__('hash', function(){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/group.js b/lib/nodes/group.js
index 8c1a4ea35..37430cd25 100644
--- a/lib/nodes/group.js
+++ b/lib/nodes/group.js
@@ -27,7 +27,7 @@ var Group = module.exports = function Group(){
  * Inherit from `Node.prototype`.
  */
 
-Group.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Group.prototype, Node.prototype);
 
 /**
  * Push the given `selector` node.
@@ -74,7 +74,7 @@ Group.prototype.__defineGetter__('hasOnlyPlaceholders', function(){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/hsla.js b/lib/nodes/hsla.js
index bea1e1249..f7870e45a 100644
--- a/lib/nodes/hsla.js
+++ b/lib/nodes/hsla.js
@@ -35,7 +35,7 @@ var HSLA = exports = module.exports = function HSLA(h,s,l,a){
  * Inherit from `Node.prototype`.
  */
 
-HSLA.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(HSLA.prototype, Node.prototype);
 
 /**
  * Return hsla(n,n,n,n).
@@ -54,7 +54,7 @@ HSLA.prototype.toString = function(){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/ident.js b/lib/nodes/ident.js
index 181f738aa..f56ab7bc7 100644
--- a/lib/nodes/ident.js
+++ b/lib/nodes/ident.js
@@ -54,11 +54,11 @@ Ident.prototype.__defineGetter__('hash', function(){
  * Inherit from `Node.prototype`.
  */
 
-Ident.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Ident.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/if.js b/lib/nodes/if.js
index e7d354d2b..8af906911 100644
--- a/lib/nodes/if.js
+++ b/lib/nodes/if.js
@@ -34,11 +34,11 @@ var If = module.exports = function If(cond, negate){
  * Inherit from `Node.prototype`.
  */
 
-If.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(If.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/import.js b/lib/nodes/import.js
index 7a3548a4b..c8e41dbaf 100644
--- a/lib/nodes/import.js
+++ b/lib/nodes/import.js
@@ -28,7 +28,7 @@ var Import = module.exports = function Import(expr, once){
  * Inherit from `Node.prototype`.
  */
 
-Import.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Import.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
diff --git a/lib/nodes/keyframes.js b/lib/nodes/keyframes.js
index e4e1271a7..70201725e 100644
--- a/lib/nodes/keyframes.js
+++ b/lib/nodes/keyframes.js
@@ -30,11 +30,11 @@ var Keyframes = module.exports = function Keyframes(segs, prefix){
  * Inherit from `Atrule.prototype`.
  */
 
-Keyframes.prototype.__proto__ = Atrule.prototype;
+Object.setPrototypeOf(Keyframes.prototype, Atrule.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/literal.js b/lib/nodes/literal.js
index 9c6e86653..f553f3740 100644
--- a/lib/nodes/literal.js
+++ b/lib/nodes/literal.js
@@ -30,7 +30,7 @@ var Literal = module.exports = function Literal(str){
  * Inherit from `Node.prototype`.
  */
 
-Literal.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Literal.prototype, Node.prototype);
 
 /**
  * Return hash.
diff --git a/lib/nodes/media.js b/lib/nodes/media.js
index 65fdf7ba4..c81f9af69 100644
--- a/lib/nodes/media.js
+++ b/lib/nodes/media.js
@@ -27,7 +27,7 @@ var Media = module.exports = function Media(val){
  * Inherit from `Atrule.prototype`.
  */
 
-Media.prototype.__proto__ = Atrule.prototype;
+Object.setPrototypeOf(Media.prototype, Atrule.prototype);
 
 /**
  * Clone this node.
diff --git a/lib/nodes/member.js b/lib/nodes/member.js
index af947388f..5249b84f0 100644
--- a/lib/nodes/member.js
+++ b/lib/nodes/member.js
@@ -29,7 +29,7 @@ var Member = module.exports = function Member(left, right){
  * Inherit from `Node.prototype`.
  */
 
-Member.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Member.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
diff --git a/lib/nodes/namespace.js b/lib/nodes/namespace.js
index 878b474ec..f9276cf6e 100644
--- a/lib/nodes/namespace.js
+++ b/lib/nodes/namespace.js
@@ -28,7 +28,7 @@ var Namespace = module.exports = function Namespace(val, prefix){
  * Inherit from `Node.prototype`.
  */
 
-Namespace.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Namespace.prototype, Node.prototype);
 
 /**
  * Return @namespace "val".
diff --git a/lib/nodes/node.js b/lib/nodes/node.js
index 6466177f7..6aa1281f4 100644
--- a/lib/nodes/node.js
+++ b/lib/nodes/node.js
@@ -32,7 +32,7 @@ function CoercionError(msg) {
  * Inherit from `Error.prototype`.
  */
 
-CoercionError.prototype.__proto__ = Error.prototype;
+Object.setPrototypeOf(CoercionError.prototype, Error.prototype);
 
 /**
  * Node constructor.
@@ -84,7 +84,7 @@ Node.prototype = {
 
   /**
    * Return this node.
-   * 
+   *
    * @return {Node}
    * @api public
    */
diff --git a/lib/nodes/null.js b/lib/nodes/null.js
index 4efea99f0..ace0f1323 100644
--- a/lib/nodes/null.js
+++ b/lib/nodes/null.js
@@ -24,7 +24,7 @@ var Null = module.exports = function Null(){};
  * Inherit from `Node.prototype`.
  */
 
-Null.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Null.prototype, Node.prototype);
 
 /**
  * Return 'Null'.
@@ -33,7 +33,7 @@ Null.prototype.__proto__ = Node.prototype;
  * @api public
  */
 
-Null.prototype.inspect = 
+Null.prototype.inspect =
 Null.prototype.toString = function(){
   return 'null';
 };
diff --git a/lib/nodes/object.js b/lib/nodes/object.js
index ed093d8d2..651e13a46 100644
--- a/lib/nodes/object.js
+++ b/lib/nodes/object.js
@@ -29,7 +29,7 @@ var Object = module.exports = function Object(){
  * Inherit from `Node.prototype`.
  */
 
-Object.prototype.__proto__ = Node.prototype;
+(global || globalThis).Object.setPrototypeOf(Object.prototype, Node.prototype);
 
 /**
  * Set `key` to `val`.
diff --git a/lib/nodes/params.js b/lib/nodes/params.js
index d7ac6d744..6860c0e47 100644
--- a/lib/nodes/params.js
+++ b/lib/nodes/params.js
@@ -40,7 +40,7 @@ Params.prototype.__defineGetter__('length', function(){
  * Inherit from `Node.prototype`.
  */
 
-Params.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Params.prototype, Node.prototype);
 
 /**
  * Push the given `node`.
@@ -55,7 +55,7 @@ Params.prototype.push = function(node){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/property.js b/lib/nodes/property.js
index 215785ac3..80f38f404 100644
--- a/lib/nodes/property.js
+++ b/lib/nodes/property.js
@@ -29,11 +29,11 @@ var Property = module.exports = function Property(segs, expr){
  * Inherit from `Node.prototype`.
  */
 
-Property.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Property.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/query-list.js b/lib/nodes/query-list.js
index 3819640b4..936919694 100644
--- a/lib/nodes/query-list.js
+++ b/lib/nodes/query-list.js
@@ -26,11 +26,11 @@ var QueryList = module.exports = function QueryList(){
  * Inherit from `Node.prototype`.
  */
 
-QueryList.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(QueryList.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/query.js b/lib/nodes/query.js
index 47a568b71..ecf5a498c 100644
--- a/lib/nodes/query.js
+++ b/lib/nodes/query.js
@@ -28,11 +28,11 @@ var Query = module.exports = function Query(){
  * Inherit from `Node.prototype`.
  */
 
-Query.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Query.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/return.js b/lib/nodes/return.js
index 003ef3801..7da671485 100644
--- a/lib/nodes/return.js
+++ b/lib/nodes/return.js
@@ -27,11 +27,11 @@ var Return = module.exports = function Return(expr){
  * Inherit from `Node.prototype`.
  */
 
-Return.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Return.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/rgba.js b/lib/nodes/rgba.js
index a961dc9cd..d76f0c56a 100644
--- a/lib/nodes/rgba.js
+++ b/lib/nodes/rgba.js
@@ -39,11 +39,11 @@ var RGBA = exports = module.exports = function RGBA(r,g,b,a){
  * Inherit from `Node.prototype`.
  */
 
-RGBA.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(RGBA.prototype, Node.prototype);
 
 /**
  * Return an `RGBA` without clamping values.
- * 
+ *
  * @param {Number} r
  * @param {Number} g
  * @param {Number} b
@@ -63,7 +63,7 @@ RGBA.withoutClamping = function(r,g,b,a){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
@@ -188,7 +188,7 @@ RGBA.prototype.multiply = function(n){
       this.r * n
     , this.g * n
     , this.b * n
-    , this.a); 
+    , this.a);
 };
 
 /**
@@ -204,7 +204,7 @@ RGBA.prototype.divide = function(n){
       this.r / n
     , this.g / n
     , this.b / n
-    , this.a); 
+    , this.a);
 };
 
 /**
@@ -338,7 +338,7 @@ exports.fromHSLA = function(hsla){
     if (h * 3 < 2) return m1 + (m2 - m1) * (2/3 - h) * 6;
     return m1;
   }
-  
+
   return new RGBA(r,g,b,a);
 };
 
diff --git a/lib/nodes/root.js b/lib/nodes/root.js
index 3bfb3c218..3e42e7c53 100644
--- a/lib/nodes/root.js
+++ b/lib/nodes/root.js
@@ -25,7 +25,7 @@ var Root = module.exports = function Root(){
  * Inherit from `Node.prototype`.
  */
 
-Root.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Root.prototype, Node.prototype);
 
 /**
  * Push a `node` to this block.
diff --git a/lib/nodes/selector.js b/lib/nodes/selector.js
index db183cc7f..8b2b61db1 100644
--- a/lib/nodes/selector.js
+++ b/lib/nodes/selector.js
@@ -30,7 +30,7 @@ var Selector = module.exports = function Selector(segs){
  * Inherit from `Node.prototype`.
  */
 
-Selector.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Selector.prototype, Node.prototype);
 
 /**
  * Return the selector string.
@@ -56,7 +56,7 @@ Selector.prototype.__defineGetter__('isPlaceholder', function(){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/string.js b/lib/nodes/string.js
index 1fd2b4504..c0dd8785d 100644
--- a/lib/nodes/string.js
+++ b/lib/nodes/string.js
@@ -37,7 +37,7 @@ var String = module.exports = function String(val, quote){
  * Inherit from `Node.prototype`.
  */
 
-String.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(String.prototype, Node.prototype);
 
 /**
  * Return quoted string.
@@ -52,7 +52,7 @@ String.prototype.toString = function(){
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/supports.js b/lib/nodes/supports.js
index ab0587837..a3dbf8390 100644
--- a/lib/nodes/supports.js
+++ b/lib/nodes/supports.js
@@ -26,7 +26,7 @@ var Supports = module.exports = function Supports(condition){
  * Inherit from `Atrule.prototype`.
  */
 
-Supports.prototype.__proto__ = Atrule.prototype;
+Object.setPrototypeOf(Supports.prototype, Atrule.prototype);
 
 /**
  * Return a clone of this node.
diff --git a/lib/nodes/ternary.js b/lib/nodes/ternary.js
index 2034170a4..16e0b10d0 100644
--- a/lib/nodes/ternary.js
+++ b/lib/nodes/ternary.js
@@ -31,11 +31,11 @@ var Ternary = module.exports = function Ternary(cond, trueExpr, falseExpr){
  * Inherit from `Node.prototype`.
  */
 
-Ternary.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Ternary.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/unaryop.js b/lib/nodes/unaryop.js
index 6ac92ab34..6cfb44c12 100644
--- a/lib/nodes/unaryop.js
+++ b/lib/nodes/unaryop.js
@@ -29,11 +29,11 @@ var UnaryOp = module.exports = function UnaryOp(op, expr){
  * Inherit from `Node.prototype`.
  */
 
-UnaryOp.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(UnaryOp.prototype, Node.prototype);
 
 /**
  * Return a clone of this node.
- * 
+ *
  * @return {Node}
  * @api public
  */
diff --git a/lib/nodes/unit.js b/lib/nodes/unit.js
index 2d38d84fa..aae54ab75 100644
--- a/lib/nodes/unit.js
+++ b/lib/nodes/unit.js
@@ -46,7 +46,7 @@ var Unit = module.exports = function Unit(val, type){
  * Inherit from `Node.prototype`.
  */
 
-Unit.prototype.__proto__ = Node.prototype;
+Object.setPrototypeOf(Unit.prototype, Node.prototype);
 
 /**
  * Return Boolean based on the unit value.
diff --git a/lib/renderer.js b/lib/renderer.js
index dd478b3fb..eb3f9407f 100644
--- a/lib/renderer.js
+++ b/lib/renderer.js
@@ -51,7 +51,7 @@ function Renderer(str, options) {
  * Inherit from `EventEmitter.prototype`.
  */
 
-Renderer.prototype.__proto__ = EventEmitter.prototype;
+Object.setPrototypeOf(Renderer.prototype, EventEmitter.prototype);
 
 /**
  * Expose events explicitly.
diff --git a/lib/stack/index.js b/lib/stack/index.js
index 9e288c62f..f8de9d0fb 100644
--- a/lib/stack/index.js
+++ b/lib/stack/index.js
@@ -19,7 +19,7 @@ var Stack = module.exports = function Stack() {
  * Inherit from `Array.prototype`.
  */
 
-Stack.prototype.__proto__ = Array.prototype;
+Object.setPrototypeOf(Stack.prototype, Array.prototype);
 
 /**
  * Push the given `frame`.
diff --git a/lib/units.js b/lib/units.js
index b26bb9842..a242a7b83 100644
--- a/lib/units.js
+++ b/lib/units.js
@@ -6,10 +6,18 @@
  */
 
 // units found in http://www.w3.org/TR/css3-values
+// and in https://www.w3.org/TR/css-values-4
 
 module.exports = [
     'em', 'ex', 'ch', 'rem' // relative lengths
-  , 'vw', 'vh', 'vmin', 'vmax' // relative viewport-percentage lengths
+
+  , 'vw', 'svw', 'lvw', 'dvw' // relative viewport-percentage lengths (including de-facto standard)
+  , 'vh', 'svh', 'lvh', 'dvh'
+  , 'vi', 'svi', 'lvi', 'dvi'
+  , 'vb', 'svb', 'lvb', 'dvb'
+  , 'vmin', 'svmin', 'lvmin', 'dvmin'
+  , 'vmax', 'svmax', 'lvmax', 'dvmax'
+
   , 'cm', 'mm', 'in', 'pt', 'pc', 'px' // absolute lengths
   , 'deg', 'grad', 'rad', 'turn' // angles
   , 's', 'ms' // times
diff --git a/lib/visitor/compiler.js b/lib/visitor/compiler.js
index 9a793339e..f4ef4a60e 100644
--- a/lib/visitor/compiler.js
+++ b/lib/visitor/compiler.js
@@ -39,7 +39,7 @@ var Compiler = module.exports = function Compiler(root, options) {
  * Inherit from `Visitor.prototype`.
  */
 
-Compiler.prototype.__proto__ = Visitor.prototype;
+Object.setPrototypeOf(Compiler.prototype, Visitor.prototype);
 
 /**
  * Compile to css, and return a string of CSS.
diff --git a/lib/visitor/deps-resolver.js b/lib/visitor/deps-resolver.js
index 94827db9c..1f2fd3089 100644
--- a/lib/visitor/deps-resolver.js
+++ b/lib/visitor/deps-resolver.js
@@ -33,7 +33,7 @@ var DepsResolver = module.exports = function DepsResolver(root, options) {
  * Inherit from `Visitor.prototype`.
  */
 
-DepsResolver.prototype.__proto__ = Visitor.prototype;
+Object.setPrototypeOf(DepsResolver.prototype, Visitor.prototype);
 
 var visit = DepsResolver.prototype.visit;
 
diff --git a/lib/visitor/evaluator.js b/lib/visitor/evaluator.js
index d60ddfcad..4aa8cf6be 100644
--- a/lib/visitor/evaluator.js
+++ b/lib/visitor/evaluator.js
@@ -144,7 +144,7 @@ var Evaluator = module.exports = function Evaluator(root, options) {
  * Inherit from `Visitor.prototype`.
  */
 
-Evaluator.prototype.__proto__ = Visitor.prototype;
+Object.setPrototypeOf(Evaluator.prototype, Visitor.prototype);
 
 /**
  * Proxy visit to expose node line numbers.
@@ -913,7 +913,7 @@ Evaluator.prototype.visitImport = function(imported){
 
   // Throw if import failed
   if (!found) throw new Error('failed to locate @' + nodeName + ' file ' + path);
-  
+
   var block = new nodes.Block;
 
   for (var i = 0, len = found.length; i < len; ++i) {
diff --git a/lib/visitor/normalizer.js b/lib/visitor/normalizer.js
index 215e6f3c5..6760c9427 100644
--- a/lib/visitor/normalizer.js
+++ b/lib/visitor/normalizer.js
@@ -40,7 +40,7 @@ var Normalizer = module.exports = function Normalizer(root, options) {
  * Inherit from `Visitor.prototype`.
  */
 
-Normalizer.prototype.__proto__ = Visitor.prototype;
+Object.setPrototypeOf(Normalizer.prototype, Visitor.prototype);
 
 /**
  * Normalize the node tree.
@@ -440,4 +440,4 @@ Normalizer.prototype._checkForPrefixedGroups = function (selector) {
       break;
   }
   return result;
-};
\ No newline at end of file
+};
diff --git a/lib/visitor/sourcemapper.js b/lib/visitor/sourcemapper.js
index 0e081104d..97e998884 100644
--- a/lib/visitor/sourcemapper.js
+++ b/lib/visitor/sourcemapper.js
@@ -58,7 +58,7 @@ var SourceMapper = module.exports = function SourceMapper(root, options){
  * Inherit from `Compiler.prototype`.
  */
 
-SourceMapper.prototype.__proto__ = Compiler.prototype;
+Object.setPrototypeOf(SourceMapper.prototype, Compiler.prototype);
 
 /**
  * Generate and write source map.
diff --git a/package.json b/package.json
index baef1a669..6480ec082 100644
--- a/package.json
+++ b/package.json
@@ -25,10 +25,11 @@
   },
   "scripts": {
     "prepublish": "npm prune",
-    "test": "mocha test/ test/middleware/ --require chai --bail --check-leaks --reporter dot"
+    "test": "mocha test/ test/middleware/ --require chai --bail --check-leaks --reporter dot",
+    "test:deno": "deno run -A deno/test.ts"
   },
   "dependencies": {
-    "@adobe/css-tools": "^4.0.1",
+    "@adobe/css-tools": "~4.2.0",
     "debug": "^4.3.2",
     "glob": "^7.1.6",
     "sax": "~1.2.4",