Remove cssnano and replace with clean-css. This fixes lack of IE9 friendly -ms prefixes in the minified stylesheet, with an added bonus of being quicker to compile.

Author: brettsmason

gulp/tasks/customizer.js

@@ -1,7 +1,7 @@
 var addSrc = require('gulp-add-src');
 var babel = require('gulp-babel');
 var concat = require('gulp-concat');
-var cssnano = require('gulp-cssnano');
+var cleancss = require('gulp-clean-css');
 var customizer = require('../../customizer/lib');
 var Vinyl = require('vinyl');
 var fs = require('fs');
@@ -95,7 +95,7 @@ gulp.task('customizer:sass', ['customizer:loadConfig', 'customizer:prepareSassDe
       browsers: COMPATIBILITY
     })]))
     .pipe(gulp.dest(path.join(OUTPUT_DIR, 'css')))
-    .pipe(cssnano())
+    .pipe(cleancss({ compatibility: 'ie9' }))
     .pipe(rename('foundation.min.css'))
     .pipe(gulp.dest(path.join(OUTPUT_DIR, 'css')));
 });

gulp/tasks/deploy.js

@@ -1,6 +1,6 @@
 var gulp = require('gulp');
 var filter = require('gulp-filter');
-var cssnano = require('gulp-cssnano');
+var cleancss = require('gulp-clean-css');
 var rename = require('gulp-rename');
 var uglify = require('gulp-uglify');
 var confirm = require('gulp-prompt').confirm;
@@ -54,7 +54,7 @@ gulp.task('deploy:dist', ['sass:foundation', 'javascript:foundation'], function(
     .pipe(plumber())
     .pipe(cssFilter)
       .pipe(gulp.dest('./dist/css'))
-      .pipe(cssnano())
+      .pipe(cleancss({ compatibility: 'ie9' }))
       .pipe(rename({ suffix: '.min' }))
       .pipe(gulp.dest('./dist/css'))
     .pipe(cssFilter.restore)
@@ -153,7 +153,7 @@ gulp.task('deploy:templates', function(done) {
 // The Customizer runs this function to generate files it needs
 gulp.task('deploy:custom', ['sass:foundation', 'javascript:foundation'], function() {
   gulp.src('./_build/assets/css/foundation.css')
-      .pipe(cssnano())
+      .pipe(cleancss({ compatibility: 'ie9' }))
       .pipe(rename('foundation.min.css'))
       .pipe(gulp.dest('./_build/assets/css'));
 

package.json

@@ -52,8 +52,8 @@
     "gulp-babel": "^6.1.1",
     "gulp-cache-bust": "~1.0.2",
     "gulp-check-deps": "^1.4.1",
+    "gulp-clean-css": "^3.3.1",
     "gulp-concat": "^2.4.3",
-    "gulp-cssnano": "^2.1.0",
     "gulp-eslint": "^3.0.1",
     "gulp-filter": "^4.0.0",
     "gulp-if": "^2.0.0",