   gulp.watch "./assets/stylus/**/*.styl", ['css:build:preview']
   gulp.watch "./templates/**/*.jade", ['preview:jade']
   gulp.watch "./contents/**/*.md", ['preview:md']
+
+# =================================================================                      
+# tools
+# =================================================================  
+
+gulp.task "checkcss", ->
+  return gulp.src(['build/css/main.css','build/**/*.html'])
+    .pipe(checkcss())
+
+
+

purifycss = require 'gulp-purifycss'
checkcss = require 'gulp-check-unused-css'
mincss = require 'gulp-clean-css'

# =================================================================                      
# high level tasks

                new RegExp('\.Aligner-*(.)\S+')
                new RegExp('\.TechSpecs-*(.)\S+')
                ]
                ))
    .pipe(gulp.dest('build/css'))

# =================================================================                      
# non aggresive css clean


gulp.task "purifycss", ->
  options = { 
    minify: true
    info: true
    rejected: true
  }
  content = ['build/css/*.css','build/**/*.html']

  return gulp.src('build/css/*.css')
    .pipe(purifycss(content, options))
    # .pipe(mincss({compatibility: 'ie8'}))
    .pipe(gulp.dest('build/css'))

# =================================================================                      

gulp.task 'cleaned', ->
  # preview with browserSync
