Grunt включает bower_components в блоке usemin

У меня есть следующий блок на моей странице index.html..

<!-- build:css(.tmp) styles/style.css -->
    <link rel="stylesheet" href="bower_components/normalize-css/normalize.css">
    <link rel="stylesheet" href="styles/main.css">
<!-- endbuild -->

Файлы css существуют правильно в моей структуре приложения, но когда я запускаю "grunt build", в результирующий файл styles/style.css входит только CSS из styles/main.css.

Я предполагаю, что мне нужно сказать Grunt, чтобы посмотреть в каталог bower_components для файлов CSS? Но я не уверен, как это сделать?

Копия моего gruntfile.js ниже...

    grunt.initConfig({
      yeoman: yeomanConfig,
      watch: {
        styles: {
          files: ['<%= yeoman.app %>/styles/{,*/}*.css'],
          tasks: ['copy:styles', 'autoprefixer']
        },
        livereload: {
          options: {
            livereload: LIVERELOAD_PORT
          },
          files: [
            '<%= yeoman.app %>/{,*/}*.html',
            '.tmp/styles/{,*/}*.css',
            '{.tmp,<%= yeoman.app %>}/scripts/{,*/}*.js',
            '<%= yeoman.app %>/images/{,*/}*.{png,jpg,jpeg,gif,webp,svg}'
          ]
        }
      },
      autoprefixer: {
        options: ['last 1 version'],
        dist: {
          files: [{
            expand: true,
            cwd: '.tmp/styles/',
            src: '{,*/}*.css',
            dest: '.tmp/styles/'
          }]
        }
      },
      connect: {
        options: {
          port: 9000,
          hostname: 'localhost'
        },
        livereload: {
          options: {
            middleware: function (connect) {
              return [
                lrSnippet,
                mountFolder(connect, '.tmp'),
                mountFolder(connect, yeomanConfig.app)
              ];
            }
          }
        },
        test: {
          options: {
            middleware: function (connect) {
              return [
                mountFolder(connect, '.tmp'),
                mountFolder(connect, 'test')
              ];
            }
          }
        },
        dist: {
          options: {
            middleware: function (connect) {
              return [
                mountFolder(connect, yeomanConfig.dist)
              ];
            }
          }
        }
      },
      open: {
        server: {
          url: 'http://localhost:<%= connect.options.port %>'
        }
      },
      clean: {
        dist: {
          files: [{
            dot: true,
            src: [
              '.tmp',
              '<%= yeoman.dist %>/*',
              '!<%= yeoman.dist %>/.git*'
            ]
          }]
        },
        server: '.tmp'
      },
      jshint: {
        options: {
          jshintrc: '.jshintrc'
        },
        all: [
          'Gruntfile.js',
          '<%= yeoman.app %>/scripts/{,*/}*.js'
        ]
      },
      rev: {
        dist: {
          files: {
            src: [
              '<%= yeoman.dist %>/scripts/{,*/}*.js',
              '<%= yeoman.dist %>/styles/{,*/}*.css',
              '<%= yeoman.dist %>/images/{,*/}*.{png,jpg,jpeg,gif,webp,svg}',
              '<%= yeoman.dist %>/styles/fonts/*'
            ]
          }
        }
      },
      useminPrepare: {
        html: '<%= yeoman.app %>/index.html',
        options: {
          dest: '<%= yeoman.dist %>'
        }
      },
      usemin: {
        html: ['<%= yeoman.dist %>/{,*/}*.html'],
        css: ['<%= yeoman.dist %>/styles/{,*/}*.css'],
        options: {
          dirs: ['<%= yeoman.dist %>']
        }
      },
      imagemin: {
        dist: {
          files: [{
            expand: true,
            cwd: '<%= yeoman.app %>/images',
            src: '{,*/}*.{png,jpg,jpeg}',
            dest: '<%= yeoman.dist %>/images'
          }]
        }
      },
      svgmin: {
        dist: {
          files: [{
            expand: true,
            cwd: '<%= yeoman.app %>/images',
            src: '{,*/}*.svg',
            dest: '<%= yeoman.dist %>/images'
          }]
        }
      },
      cssmin: {

      },
      htmlmin: {
        dist: {
          options: {

          },
          files: [{
            expand: true,
            cwd: '<%= yeoman.app %>',
            src: ['*.html', 'views/*.html'],
            dest: '<%= yeoman.dist %>'
          }]
        }
      },
      // Put files not handled in other tasks here
      copy: {
        dist: {
          files: [{
            expand: true,
            dot: true,
            cwd: '<%= yeoman.app %>',
            dest: '<%= yeoman.dist %>',
            src: [
              '*.{ico,png,txt}',
              '.htaccess',
              'bower_components/**/*',
              'images/{,*/}*.{gif,webp}',
              'styles/fonts/*'
            ]
          }, {
            expand: true,
            cwd: '.tmp/images',
            dest: '<%= yeoman.dist %>/images',
            src: [
              'generated/*'
            ]
          }]
        },
        styles: {
          expand: true,
          cwd: '<%= yeoman.app %>/styles',
          dest: '.tmp/styles/',
          src: '{,*/}*.css'
        }
      },
      concurrent: {
        server: [
          'copy:styles'
        ],
        test: [
          'copy:styles'
        ],
        dist: [
          'copy:styles',
          'imagemin',
          'svgmin',
          'htmlmin'
        ]
      },
      karma: {
        unit: {
          configFile: 'karma.conf.js',
          singleRun: true
        }
      },
      cdnify: {
        dist: {
          html: ['<%= yeoman.dist %>/*.html']
        }
      },
      ngmin: {
        dist: {
          files: [{
            expand: true,
            cwd: '<%= yeoman.dist %>/scripts',
            src: '*.js',
            dest: '<%= yeoman.dist %>/scripts'
          }]
        }
      },
      uglify: {
        dist: {
          files: {
            '<%= yeoman.dist %>/scripts/scripts.js': [
              '<%= yeoman.dist %>/scripts/scripts.js'
            ]
          }
        }
      }
    });