Brunch / brunch-config.js - Semantic-UI-CSS Help

Can’t get Brunch to load the CSS portion. It loads JQuery and the JavaScript portion of Semantic just fine, though. Any thoughts?

files: {
javascripts: {
  joinTo: "js/app.js",
  order: {
    before: [
      "jquery/dist/jquery.js",
      "node_modules/semantic-ui-css/semantic.js"
    ]
  }
},
stylesheets: {
  joinTo: "css/app.css",
  order: {
    before: ["node_modules/semantic-ui-css/semantic.css"],
    after: ["web/static/css/app.css"] // concat app.css last
  }
},

Decided to just copy everything into the static/vendor folder.

files: {
    javascripts: {
      joinTo: {
        "js/app.js": /^(web\/static\/js)/,
        "js/vendor.js": /^(web\/static\/vendor)|(deps)/
      }
    },
    stylesheets: {
      joinTo: {
        "css/app.css": /^(web\/static\/css)/,
        "css/vendor.css": /^(web\/static\/vendor)/
      }
    },

This works fine, except now I receive:

Error: Cannot find module 'phoenix_html' from 'web/static/js/app.js'

Must be something to do with separating the vendor files, because once I remove that and go back to the default configuration, no errors.