DMN-JS Development Env setup question

I’m trying to extend dmn-js. I have followed following link to setup project locally

https://github.com/bpmn-io/dmn-js/blob/develop/.github/CONTRIBUTING.md ( Setting up the project locally)

After our changes, we followed the following steps to test with our application

  1. dmn-js/npm run travis
  2. cd dmn-js/packages
  3. created npm links for all the 5 packages (dmn-js/packages/dmn-js-*)
  4. from my project root (/foo_project), I have linked them using npm link <> (Repeated for all dmn-js 5 packages)
  5. from my foo_project/style.css imported all css files that are insdie dmn-js/packages/dmn-js/dist/assets

issue: Styles sheets not applied properly. as we investigated whereever dmn-js-* styles sheets used “var” is not working. If we fall back to npm install dmn-js, style sheets are working, but if we include dmn-js-extension, var is not working.

Question did we follow correct steps to setup our development environment?

btw we have changed rollup.clonfig.js

const distros = [
  {
    input: 'Viewer',
    output: 'dmn-viewer'
  },
  {
    input: 'NavigatedViewer',
    output: 'dmn-navigated-viewer'
  },
  {
    input: 'Modeler',
    output: 'dmn-modeler'
  },
  {
    input: 'extension/ViewerExt',
    output: 'dmn-viewer-ext'
  },
  {
    input: 'extension/ModelerExt',
    output: 'dmn-modeler-ext'
  }
];

const configs = distros.reduce(function(configs, distro) {
  const {
    input,
    output
  } = distro;

  return [
    ...configs,
    {
      input: `./src/${input}.js`,
      output: {
        name: 'DmnJS',
        file: `${outputDir}/${output}.development.js`,
        format: 'umd'
      },
      plugins: pgl([
        banner(output)
      ])
    },
    {
      input: `./src/${input}.js`,
      output: {
        name: 'DmnJS',
        file: `${outputDir}/${output}.production.min.js`,
        format: 'umd'
      },
      plugins: pgl([
        banner(output, true),
        uglify({
          output: {
            comments: /license|@preserve/
          }
        })
      ])
    }
  ];
}, []);

It seems using npm run travis is not the command to run! I see following differences

  1. npm install dmn-js --> i see all .css files under nodemodules/dmn-js/dist/assets don’t have var(). all css variables replaced with actual values

  2. local project development setup (using npm run travis and then npm link) is not replacing css variables.

can some one help me how to fix step#2 above to get css files just like step#1 above