gulpfile.js

const gulp = require('gulp');
const browserSync = require('browser-sync');
const sass = require('gulp-sass')(require('sass'));
const rename = require("gulp-rename");
const cleanCSS = require('gulp-clean-css');
const autoprefixer = require('gulp-autoprefixer');

// Static server
gulp.task('server', function () {
    browserSync.init({
        server: {
            baseDir: "src"
        }
    });
});

gulp.task('styles', function () {
    return gulp.src("src/sass/**/*.+(scss|sass)")
        .pipe(sass({ outputStyle: 'compressed' }).on('error', sass.logError))
        .pipe(rename({
            prefix: "",
            suffix: ".min"
        }))
        .pipe(autoprefixer())
        .pipe(cleanCSS({ compatibility: 'ie8' }))
        .pipe(gulp.dest("src/css"))
        .pipe(browserSync.stream());
});

gulp.task('watch', function () {
    gulp.watch("src/sass/**/*.+(scss|sass)", gulp.parallel("styles"))
    gulp.watch("src/*.html").on("change", browserSync.reload)
});

gulp.task('default', gulp.parallel('watch', 'server', 'styles'));