Missed during rebase

gulpfile.js

@@ -12,7 +12,7 @@ var eslint       = require('gulp-eslint');
 var lazypipe     = require('lazypipe');
 var less         = require('gulp-less');
 var merge        = require('merge-stream');
-var minifyCss    = require('gulp-minify-css');
+var cssNano      = require('gulp-cssnano');
 var plumber      = require('gulp-plumber');
 var rev          = require('gulp-rev');
 var runSequence  = require('run-sequence');
@@ -105,8 +105,7 @@ var cssTasks = function(filename) {
       ]
     })
     .pipe(cssNano, {
-      advanced: false,
-      rebase: false
+      safe: true
     })
     .pipe(function() {
       return gulpif(enabled.rev, rev());