#2952390 off-canvas css renamer - download to docroot/renamer, run npm install, then "grunt"

Gruntfile.js

const glob = require('glob');

let files = {};
glob.sync('../core/**/off-canvas*.css').forEach((file) => {
  files[file] = file;
});

module.exports = (grunt) => {
  grunt.loadNpmTasks('grunt-css-selectors');

  grunt.initConfig({
    css_selectors: {
      options: {
        mutations: [
          // Append to end of string or before the first colon.
          // Ex: #foo => #foo:not(...), #foo:after => #foo:not(...):after
          {search: /(?=:)|$/, replace: ':not(.js-off-canvas-ignore)'}
        ],
        indent: '  ',
      },
      your_target: {
        files: files,
      },
    },
  });

  grunt.registerTask('default', ['css_selectors']);
}

package.json

{
  "name": "renamer",
  "version": "1.0.0",
  "devDependencies": {
    "glob": "^7.1.2",
    "grunt": "^1.0.2",
    "grunt-css-selectors": "^1.3.0"
  }
}