var gulp = require('gulp')
var concat = require('gulp-concat');
var cleanCSS = require('gulp-clean-css');
var sourcemaps = require('gulp-sourcemaps');
var concatCss = require('gulp-concat-css');
gulp.task('minify-css', function() {
return gulp.src('./css/*.css')
.pipe(sourcemaps.init())
.pipe(cleanCSS())
.pipe(sourcemaps.write())
.pipe(concatCss('all.css'))
.pipe(gulp.dest('dist'));
});