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A pretty common setup for front-end design work is to use Sass to compile .scss files into a single .css file. It's also pretty common to use a CSS Reset, such as normalize.css or sanitize.css, to reset your CSS to a common base. For that CSS Reset to work, it needs to be included before any of the app-specific CSS, so you can override it and not the other way around. You could just copy the normalize.css file into your project and link it separately in your HTML, or you could even stick it in your scss/ directory and have Sass process it unnecessarily. But what if you want to just install it from npm and have gulp include it in your output app.css file? Here's a quick and easy way to do that in your gulpfile.js.

This assumes you have a basic gulp setup with:

$ npm install -D gulp gulp-sass gulp-concat

And assuming you have a gulp.task() like the following:

var gulp = require('gulp'),
    sass = require('gulp-sass'),
    concat = require('gulp-concat');

gulp.task('css', function () {
    return gulp.src('scss/**/*.scss')
        .pipe(sass().on('error', sass.logError))
        .pipe(concat('app.css'))
        .pipe(gulp.dest('css/'));
});

Now you install normalize.css with the following:

$ npm install --save normalize.css

which will stick it in your node_modules/ subdirectory. How do you tell Gulp to just include that file, then run Sass on your *.scss files, and output it all to css/app.css? The solution is to create two streams and use the package merge-stream to merge them together before concatenating. So install merge-stream:

$ npm install -D merge-stream

Then create 2 separate streams, one for the normalize CSS (and any other NPM installed CSS files you might want to use), the other for your Sass processed files. Finally merge them, concatenate, and output. Your gulpfile.js will look like the following:

var gulp = require('gulp'),
    sass = require('gulp-sass'),
    concat = require('gulp-concat'),
    merge = require('merge-stream');

gulp.task('css', function () {
    const reset = gulp.src('node_modules/normalize.css/normalize.css');

    const scss = gulp.src('scss/**/*.scss')
        .pipe(sass().on('error', sass.logError));

    return merge(reset, scss)
        .pipe(concat('app.css'))
        .pipe(gulp.dest('css/'));
});

Your css/app.css will now contain the contents of normalize.css followed by all of your CSS compiled by Sass. Whenever you update your normalize.css package from NPM, your output will be automatically updated. Unless you pin a specific version of normalize.css which may be a good idea depending on your project.