[1067] Can't use sass library (bulma) in global css

I have this error on version "1.0.0-alpha.5":

/home/vladzur/MisProyectos/vladzur-front/node_modules/bulma/bulma.sass:2
@charset "utf-8"
^
SyntaxError: Invalid or unexpected token
    at createScript (vm.js:56:10)
    at Object.runInThisContext (vm.js:97:10)
    at Module._compile (module.js:542:28)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at r (/home/vladzur/MisProyectos/vladzur-front/node_modules/vue-server-renderer/build.js:5812:16)
    at Object.<anonymous> (webpack:/external "bulma":1:0)
    at __webpack_require__ (webpack:/webpack/bootstrap 594496abdc56668c5e68:25:0)
    at Object.module.exports.Object.defineProperty.value (server-bundle.js:1696:64)
    at __webpack_require__ (webpack:/webpack/bootstrap 594496abdc56668c5e68:25:0)
    at Object.<anonymous> (.nuxt/App.vue:3:0)
    at __webpack_require__ (webpack:/webpack/bootstrap 594496abdc56668c5e68:25:0)

I have this dev dependencies:

"devDependencies": {
    "babel-eslint": "^7.1.1",
    "eslint": "^3.15.0",
    "eslint-config-standard": "^6.2.1",
    "eslint-loader": "^1.6.1",
    "eslint-plugin-html": "^2.0.0",
    "eslint-plugin-promise": "^3.4.1",
    "eslint-plugin-standard": "^2.0.1",
    "node-sass": "^4.5.3",
    "sass-loader": "^6.0.6"
  }

And the nuxt.config.js

css: [
    {src: 'bulma', lang: 'sass'}
  ],