gulpfile.js

var gulp = require('gulp');
var sourcemaps = require('gulp-sourcemaps');

// Automatic browser refreshing with browser-sync
var browserSync = require('browser-sync').create();

// Stylus
var stylus = require('gulp-stylus');
var postStylus = require('poststylus');

// Plugins for stylus
var autoprefixer = require('autoprefixer');
var lost = require('lost');
var rupture = require('rupture');

// Compile stylus files
gulp.task('stylus', function () {
    gulp.src('app/stylus/app.styl')
        .pipe(sourcemaps.init())
        .pipe(stylus({
            use: [
                postStylus([
                    autoprefixer({ browsers: ['last 2 versions'] }),
                    lost
                ]),
                rupture()
            ]
        }))
        .pipe(sourcemaps.write())
        .pipe(gulp.dest('app/css'))
        .pipe(browserSync.stream());
});

// Static Server + watching stylus/html files
gulp.task('serve', ['stylus'], function() {

    browserSync.init({
        server: "./app"
    });

    gulp.watch("app/stylus/*/**.styl", ['stylus']);
    gulp.watch("app/*.html").on('change', browserSync.reload);
});

gulp.task('default', ['serve']);