code: function activatePostCSSPlugins(config) {
    const plugins = [];
  
    if (config.lintRules || config.lintRules !== "") {
      // TODO: Throw easy-to-understand error message
      // incorrect path? (ex. "lintRules": "aaa")
      // typo? (ex. "lintRules": "stylelint-config-suitcs")
      const lintRules = require(config.lintRules);
  
      if (lintRules.rules) {
        plugins.push(stylelint(lintRules));
      } else {
        throw new Error("Illegal lint rule: \"rules\" property is not found.");
      }
    }
  
    if (config.browsers && config.browsers !== "") {
      plugins.push(autoprefixer(config.browsers));
    }
  
    plugins.push(cssfmt);
    plugins.push(reporter);
  
    return plugins;
  }
docs: Activating PostCSS plugins
  @param {Object} config - Kotori config object
  @returns {Function[]} PostCSS plugins list
  @private