diff --git a/cppjswasm/.gitattributes b/cppjswasm/.gitattributes
index df3e022..971a600 100644
--- a/cppjswasm/.gitattributes
+++ b/cppjswasm/.gitattributes
@@ -9,7 +9,6 @@ Makefile linguist-documentation
 *.html text=auto eol=lf
 *.js text=auto eol=lf
 *.json text=auto eol=lf
-*.less text=auto eol=lf
 *.md text=auto eol=lf
 *.py text=auto eol=lf
 *.toml text=auto eol=lf
diff --git a/cppjswasm/js/build.mjs.jinja b/cppjswasm/js/build.mjs.jinja
index e8f3e67..ca1555b 100644
--- a/cppjswasm/js/build.mjs.jinja
+++ b/cppjswasm/js/build.mjs.jinja
@@ -1,10 +1,9 @@
 import { NodeModulesExternal } from "@finos/perspective-esbuild-plugin/external.js";
 import { build } from "@finos/perspective-esbuild-plugin/build.js";
-import { BuildCss } from "@prospective.co/procss/target/cjs/procss.js";
+import { transform } from "lightningcss";
 import { getarg } from "./tools/getarg.mjs";
 import fs from "fs";
 import cpy from "cpy";
-import path_mod from "path";
 
 const DEBUG = getarg("--debug");
 
@@ -40,31 +39,29 @@ const BUILD = [
 
 async function compile_css() {
   const process_path = (path) => {
-    const outpath = path.replace("src/less", "dist/css");
+    const outpath = path.replace("src/css", "dist/css");
     fs.mkdirSync(outpath, { recursive: true });
 
-    fs.readdirSync(path).forEach((file_or_folder) => {
-      if (file_or_folder.endsWith(".less")) {
-        const outfile = file_or_folder.replace(".less", ".css");
-        const builder = new BuildCss("");
-        builder.add(
-          `${path}/${file_or_folder}`,
-          fs
-            .readFileSync(path_mod.join(`${path}/${file_or_folder}`))
-            .toString(),
-        );
-        fs.writeFileSync(
-          `${path.replace("src/less", "dist/css")}/${outfile}`,
-          builder.compile().get(outfile),
-        );
-      } else {
-        process_path(`${path}/${file_or_folder}`);
+    fs.readdirSync(path, { withFileTypes: true }).forEach((entry) => {
+      const input = `${path}/${entry.name}`;
+      const output = `${outpath}/${entry.name}`;
+
+      if (entry.isDirectory()) {
+        process_path(input);
+      } else if (entry.isFile() && entry.name.endsWith(".css")) {
+        const source = fs.readFileSync(input);
+        const { code } = transform({
+          filename: entry.name,
+          code: source,
+          minify: !DEBUG,
+          sourceMap: false,
+        });
+        fs.writeFileSync(output, code);
       }
     });
   };
-  // recursively process all less files in src/less
-  process_path("src/less");
-  cpy("src/css/*", "dist/css/");
+
+  process_path("src/css");
 }
 
 async function copy_html() {
diff --git a/cppjswasm/js/package.json.jinja b/cppjswasm/js/package.json.jinja
index 72edc33..e80314f 100644
--- a/cppjswasm/js/package.json.jinja
+++ b/cppjswasm/js/package.json.jinja
@@ -32,10 +32,10 @@
     "build": "npm-run-all build:cpp build:prod",
     "clean": "rm -rf dist lib playwright-report ../{{module}}/extension",
     "dev": "npm-run-all -p start watch",
-    "lint:js": "prettier --check \"src/**/*.{js,ts,jsx,tsx,less,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
+    "lint:js": "prettier --check \"src/**/*.{js,ts,jsx,tsx,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
     "lint:cpp": "clang-format --dry-run -Werror -style=file:../.clang-format src/cpp/*.cpp",
     "lint": "npm-run-all lint:*",
-    "fix:js": "prettier  --write \"src/**/*.{js,ts,jsx,tsx,less,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
+    "fix:js": "prettier  --write \"src/**/*.{js,ts,jsx,tsx,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
     "fix:cpp": "clang-format -i -style=file:../.clang-format src/cpp/*.cpp",
     "fix": "npm-run-all fix:*",
     "preinstall": "npx only-allow pnpm",
@@ -44,16 +44,15 @@
     "start:tests": "http-server -p 3000 ",
     "test:js": "playwright test",
     "test": "npm-run-all test:*",
-    "watch": "nodemon --watch src -e ts,less,html,cpp,hpp --exec \"pnpm build:debug\""
+    "watch": "nodemon --watch src -e ts,css,html,cpp,hpp --exec \"pnpm build:debug\""
   },
   "dependencies": {},
   "devDependencies": {
     "@finos/perspective-esbuild-plugin": "^3.2.1",
     "@playwright/test": "^1.56.1",
-    "@prospective.co/procss": "^0.1.17",
     "cpy": "^12.1.0",
     "esbuild": "^0.27.2",
-    "esbuild-plugin-less": "^1.3.35",
+    "lightningcss": "^1.29.3",
     "http-server": "^14.1.1",
     "nodemon": "^3.1.10",
     "npm-run-all": "^4.1.5",
diff --git a/cppjswasm/js/src/less/index.less b/cppjswasm/js/src/css/index.css
similarity index 100%
rename from cppjswasm/js/src/less/index.less
rename to cppjswasm/js/src/css/index.css
diff --git a/js/.gitattributes b/js/.gitattributes
index bb7085b..aaf2698 100644
--- a/js/.gitattributes
+++ b/js/.gitattributes
@@ -7,7 +7,6 @@ Makefile linguist-documentation
 *.html text=auto eol=lf
 *.js text=auto eol=lf
 *.json text=auto eol=lf
-*.less text=auto eol=lf
 *.md text=auto eol=lf
 *.py text=auto eol=lf
 *.toml text=auto eol=lf
diff --git a/js/js/build.mjs.jinja b/js/js/build.mjs.jinja
index e8f3e67..ca1555b 100644
--- a/js/js/build.mjs.jinja
+++ b/js/js/build.mjs.jinja
@@ -1,10 +1,9 @@
 import { NodeModulesExternal } from "@finos/perspective-esbuild-plugin/external.js";
 import { build } from "@finos/perspective-esbuild-plugin/build.js";
-import { BuildCss } from "@prospective.co/procss/target/cjs/procss.js";
+import { transform } from "lightningcss";
 import { getarg } from "./tools/getarg.mjs";
 import fs from "fs";
 import cpy from "cpy";
-import path_mod from "path";
 
 const DEBUG = getarg("--debug");
 
@@ -40,31 +39,29 @@ const BUILD = [
 
 async function compile_css() {
   const process_path = (path) => {
-    const outpath = path.replace("src/less", "dist/css");
+    const outpath = path.replace("src/css", "dist/css");
     fs.mkdirSync(outpath, { recursive: true });
 
-    fs.readdirSync(path).forEach((file_or_folder) => {
-      if (file_or_folder.endsWith(".less")) {
-        const outfile = file_or_folder.replace(".less", ".css");
-        const builder = new BuildCss("");
-        builder.add(
-          `${path}/${file_or_folder}`,
-          fs
-            .readFileSync(path_mod.join(`${path}/${file_or_folder}`))
-            .toString(),
-        );
-        fs.writeFileSync(
-          `${path.replace("src/less", "dist/css")}/${outfile}`,
-          builder.compile().get(outfile),
-        );
-      } else {
-        process_path(`${path}/${file_or_folder}`);
+    fs.readdirSync(path, { withFileTypes: true }).forEach((entry) => {
+      const input = `${path}/${entry.name}`;
+      const output = `${outpath}/${entry.name}`;
+
+      if (entry.isDirectory()) {
+        process_path(input);
+      } else if (entry.isFile() && entry.name.endsWith(".css")) {
+        const source = fs.readFileSync(input);
+        const { code } = transform({
+          filename: entry.name,
+          code: source,
+          minify: !DEBUG,
+          sourceMap: false,
+        });
+        fs.writeFileSync(output, code);
       }
     });
   };
-  // recursively process all less files in src/less
-  process_path("src/less");
-  cpy("src/css/*", "dist/css/");
+
+  process_path("src/css");
 }
 
 async function copy_html() {
diff --git a/js/js/package.json.jinja b/js/js/package.json.jinja
index 66ae3ff..9cd6a7b 100644
--- a/js/js/package.json.jinja
+++ b/js/js/package.json.jinja
@@ -30,23 +30,22 @@
     "build": "node build.mjs",
     "clean": "rm -rf dist playwright-report ../{{module}}/extension",
     "dev": "npm-run-all -p start watch",
-    "lint": "prettier --check \"src/**/*.{js,ts,jsx,tsx,less,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
-    "fix": "prettier  --write \"src/**/*.{js,ts,jsx,tsx,less,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
+    "lint": "prettier --check \"src/**/*.{js,ts,jsx,tsx,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
+    "fix": "prettier  --write \"src/**/*.{js,ts,jsx,tsx,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
     "preinstall": "npx only-allow pnpm",
     "prepack": "npm run build",
     "start": "http-server -p 3000 -o examples/",
     "start:tests": "http-server -p 3000 ",
     "test": "TZ=UTC playwright test",
-    "watch": "nodemon --watch src -e ts,less,html --exec \"pnpm build:debug\""
+    "watch": "nodemon --watch src -e ts,css,html --exec \"pnpm build:debug\""
   },
   "dependencies": {},
   "devDependencies": {
     "@finos/perspective-esbuild-plugin": "^3.2.1",
     "@playwright/test": "^1.56.1",
-    "@prospective.co/procss": "^0.1.17",
     "cpy": "^12.1.0",
     "esbuild": "^0.27.2",
-    "esbuild-plugin-less": "^1.3.35",
+    "lightningcss": "^1.29.3",
     "http-server": "^14.1.1",
     "nodemon": "^3.1.10",
     "npm-run-all": "^4.1.5",
diff --git a/js/js/src/less/index.less b/js/js/src/css/index.css
similarity index 100%
rename from js/js/src/less/index.less
rename to js/js/src/css/index.css
diff --git a/jupyter/.gitattributes b/jupyter/.gitattributes
index bb7085b..aaf2698 100644
--- a/jupyter/.gitattributes
+++ b/jupyter/.gitattributes
@@ -7,7 +7,6 @@ Makefile linguist-documentation
 *.html text=auto eol=lf
 *.js text=auto eol=lf
 *.json text=auto eol=lf
-*.less text=auto eol=lf
 *.md text=auto eol=lf
 *.py text=auto eol=lf
 *.toml text=auto eol=lf
diff --git a/jupyter/js/jest.config.js b/jupyter/js/jest.config.js
index 764a009..45f3f7b 100644
--- a/jupyter/js/jest.config.js
+++ b/jupyter/js/jest.config.js
@@ -18,7 +18,7 @@ const esModules = [
 module.exports = {
   moduleDirectories: ["node_modules", "src", "tests"],
   moduleNameMapper: {
-    "\\.(css|less|sass|scss)$": "<rootDir>/tests/styleMock.js",
+    "\\.(css|sass|scss)$": "<rootDir>/tests/styleMock.js",
     "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/tests/fileMock.js",
   },
   reporters: [ "default", "jest-junit" ],
@@ -26,7 +26,7 @@ module.exports = {
   testEnvironment: "jsdom",
   transform: {
     "^.+\\.jsx?$": "babel-jest",
-    ".+\\.(css|styl|less|sass|scss)$": "jest-transform-css",
+    ".+\\.(css|styl|sass|scss)$": "jest-transform-css",
   },
   transformIgnorePatterns: [`/node_modules/.pnpm/(?!(${esModules}))`],
 };
diff --git a/rustjswasm/.gitattributes b/rustjswasm/.gitattributes
index e3e8131..f048eda 100644
--- a/rustjswasm/.gitattributes
+++ b/rustjswasm/.gitattributes
@@ -7,7 +7,6 @@ Makefile linguist-documentation
 *.html text=auto eol=lf
 *.js text=auto eol=lf
 *.json text=auto eol=lf
-*.less text=auto eol=lf
 *.md text=auto eol=lf
 *.py text=auto eol=lf
 *.rs text=auto eol=lf
diff --git a/rustjswasm/js/build.mjs.jinja b/rustjswasm/js/build.mjs.jinja
index e8f3e67..ca1555b 100644
--- a/rustjswasm/js/build.mjs.jinja
+++ b/rustjswasm/js/build.mjs.jinja
@@ -1,10 +1,9 @@
 import { NodeModulesExternal } from "@finos/perspective-esbuild-plugin/external.js";
 import { build } from "@finos/perspective-esbuild-plugin/build.js";
-import { BuildCss } from "@prospective.co/procss/target/cjs/procss.js";
+import { transform } from "lightningcss";
 import { getarg } from "./tools/getarg.mjs";
 import fs from "fs";
 import cpy from "cpy";
-import path_mod from "path";
 
 const DEBUG = getarg("--debug");
 
@@ -40,31 +39,29 @@ const BUILD = [
 
 async function compile_css() {
   const process_path = (path) => {
-    const outpath = path.replace("src/less", "dist/css");
+    const outpath = path.replace("src/css", "dist/css");
     fs.mkdirSync(outpath, { recursive: true });
 
-    fs.readdirSync(path).forEach((file_or_folder) => {
-      if (file_or_folder.endsWith(".less")) {
-        const outfile = file_or_folder.replace(".less", ".css");
-        const builder = new BuildCss("");
-        builder.add(
-          `${path}/${file_or_folder}`,
-          fs
-            .readFileSync(path_mod.join(`${path}/${file_or_folder}`))
-            .toString(),
-        );
-        fs.writeFileSync(
-          `${path.replace("src/less", "dist/css")}/${outfile}`,
-          builder.compile().get(outfile),
-        );
-      } else {
-        process_path(`${path}/${file_or_folder}`);
+    fs.readdirSync(path, { withFileTypes: true }).forEach((entry) => {
+      const input = `${path}/${entry.name}`;
+      const output = `${outpath}/${entry.name}`;
+
+      if (entry.isDirectory()) {
+        process_path(input);
+      } else if (entry.isFile() && entry.name.endsWith(".css")) {
+        const source = fs.readFileSync(input);
+        const { code } = transform({
+          filename: entry.name,
+          code: source,
+          minify: !DEBUG,
+          sourceMap: false,
+        });
+        fs.writeFileSync(output, code);
       }
     });
   };
-  // recursively process all less files in src/less
-  process_path("src/less");
-  cpy("src/css/*", "dist/css/");
+
+  process_path("src/css");
 }
 
 async function copy_html() {
diff --git a/rustjswasm/js/package.json.jinja b/rustjswasm/js/package.json.jinja
index 1d9d44b..977bd40 100644
--- a/rustjswasm/js/package.json.jinja
+++ b/rustjswasm/js/package.json.jinja
@@ -34,10 +34,10 @@
     "build": "npm-run-all build:rust build:wasm-bindgen build:prod",
     "clean": "rm -rf dist lib playwright-report ../{{module}}/extension",
     "dev": "npm-run-all -p start watch",
-    "lint:js": "prettier --check \"src/**/*.{js,ts,jsx,tsx,less,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
+    "lint:js": "prettier --check \"src/**/*.{js,ts,jsx,tsx,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
     "lint:rust": "cargo clippy --all-features && cargo fmt --all -- --check",
     "lint": "npm-run-all lint:*",
-    "fix:js": "prettier  --write \"src/**/*.{js,ts,jsx,tsx,less,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
+    "fix:js": "prettier  --write \"src/**/*.{js,ts,jsx,tsx,css}\" \"tests/**/*.{js,ts,jsx,tsx}\" \"*.mjs\" \"*.json\"",
     "fix:rust": "cargo fmt --all",
     "fix": "npm-run-all fix:*",
     "preinstall": "npx only-allow pnpm",
@@ -47,16 +47,15 @@
     "test:js": "playwright test",
     "test:rust": "cargo test -- --show-output",
     "test": "npm-run-all test:rust test:js",
-    "watch": "nodemon --watch src -e ts,less,html --exec \"pnpm build:debug\""
+    "watch": "nodemon --watch src -e ts,css,html --exec \"pnpm build:debug\""
   },
   "dependencies": {},
   "devDependencies": {
     "@finos/perspective-esbuild-plugin": "^3.2.1",
     "@playwright/test": "^1.56.1",
-    "@prospective.co/procss": "^0.1.17",
     "cpy": "^12.1.0",
     "esbuild": "^0.27.2",
-    "esbuild-plugin-less": "^1.3.35",
+    "lightningcss": "^1.29.3",
     "http-server": "^14.1.1",
     "nodemon": "^3.1.10",
     "npm-run-all": "^4.1.5",
diff --git a/rustjswasm/js/src/less/index.less b/rustjswasm/js/src/css/index.css
similarity index 100%
rename from rustjswasm/js/src/less/index.less
rename to rustjswasm/js/src/css/index.css