The browser is not updated when saving scss and css files, only after saving index.html?

Question

Sass

The update happens only after index.html is saved

let project_folder = require("path").basename(__dirname);
let source_folder = "src";

let fs = require('fs');

let path = {
build: {
html: project_folder + "/",
css: project_folder + "/css/",
js: project_folder + "/js/",
img: project_folder + "/img/",
fonts: project_folder + " /fonts/",
},
src: {
html: [source_folder + "/*.html", "!" + source_folder + "/_*.html"],
css: [source_folder + "/scss/main.scss", source_folder + "/scss/*.css"],
img: source_folder + "/img/**/*.{jpg,png,svg,gif,ico,webp}",
fonts: source_folder + "/fonts/*.ttf",
},
watch: {
html: source_folder + "/**/*.html",
css: source_folder + "/scss/**/*.scss",
js: source_folder + "/js/**/*.js",
img: source_folder + "/img/ **/*.{jpg,png,svg,gif,ico,webp}",
},
clean: "./" + project_folder + "/"
}

let { src, dest } = require('gulp'),
gulp = require('gulp'),
browsersync = require("browser-sync").create(),
fileinclude = require("gulp-file-include"),
del = require("del"),
scss = require("gulp-sass"),
autoprefixer = require("gulp-autoprefixer"),
group_media = require("gulp-group-css-media-queries"),
clean_css = require("gulp-clean-css"),
rename = require("gulp-rename" ),
uglify = require("gulp-uglify-es").default,
imagemin = require("gulp-imagemin"),
webp = require("gulp-webp"),
webpcss = require("gulp-webpcss"),
webphtml = require("gulp-webp-html"),
svgSprite = require("gulp-svg-sprite"),
ttf2woff = require("gulp-ttf2woff"),
ttf2woff2 = require("gulp-ttf2woff2"),
fonter = require("gulp font");

function browserSync(params) {
browsersync.init({
server: {
baseDir: "./" + project_folder + "/"
},
port: 3000,
notify: false
})
}

function html() {
return src(path.src.html)
.pipe(fileinclude())
.pipe(webphtml( ))
.pipe(dest(path.build.html))
.pipe(browsersync.stream())
}

function css() {
return src(path.src.css)
.pipe(
scss({
outputStyle: "expanded"
} )
)
.pipe(group_media())
.pipe(
autoprefixer({
grid: "autoplace",
overrideBrowserslist: [
"last 5 version",
"> 1%",
"IE 10"
],
cascade: true
})
)
.pipe(webpcss({
webpClass: '.webp',
noWebpClass: '.no-webp'
})
)
.pipe(dest(path.build.css))
.pipe(clean_css())
.pipe(
rename({
extname: ".min.css"
})
)
.pipe(dest(path.build.css))
. pipe(browsersync.stream())
}

function js() {
return src(path.src.js)
.pipe(fileinclude())
.pipe(dest(path.build.js))
.pipe(uglify())
.pipe(
rename({
extname: ". min.js"
})
)
.pipe(dest(path.build.js))
.pipe(browsersync.stream())
}

function images() {
return src(path.src.img)
.pipe(
webp({
quality : 70
})
)
.pipe(dest(path.build.img))
.pipe(src(path.src.img))
.pipe(
imagemin({
progressive: true,
svgoOlugins: [{ removeViewBox: false }],
interlaced: true,
optimizationLevel: 3 // 0 to 7
})
)
.pipe(dest(path.build.img))
.pipe(browsersync.stream())
}

gulp.task("otf2ttf", function () {
return gulp.src([source_folder + '/fonts/*.otf'])
.pipe(fonter({
formats: ['ttf']
}))
.pipe( dest(source_folder + '/fonts/'));
})

gulp.task("svgSprite", function () {
return gulp.src([source_folder + '/iconsprite/*.svg'])
.pipe(svgSprite({
mode: {
stack: {
sprite: "../icons/icons.svg",
example: true
}
},
}
))
.pipe(dest(path.build.img))
})

function fonts(params) {
src( path.src.fonts)
.pipe(ttf2woff())
.pipe(dest(path.build.fonts));
return src(path.src.fonts)
.pipe(ttf2woff2())
.pipe(dest(path.build.fonts));
}

function fontsStyle(params) {
let file_content = fs.readFileSync(source_folder + '/scss/fonts.scss');
if (file_content == '') {
fs.writeFile(source_folder + '/scss/fonts.scss', '', cb);
return fs.readdir(path.build.fonts, function (err, items) {
if (items) {
let c_fontname;
for (var i = 0; i < items.length; i++) {
let fontname = items[i]. split('.');
fontname = fontname[0];
if (c_fontname != fontname) {
fs.appendFile(source_folder + '/scss/fonts.scss', '@include font("' + fontname + '", "' + fontname + '", "400", "normal");\r\n', cb);
}
c_fontname = fontname;
}
}

function cb() { }

function watchFiles(params) {
gulp.watch([path.watch.html], html);
gulp.watch([path.watch.css], css);
gulp.watch([path.watch.js], js);
gulp.watch([path.watch.img], images);
}

function clean(params) {
return del(path.clean);
}

let build = gulp.series(clean, gulp.parallel(js, css, html, images, fonts), fontsStyle);
let watch = gulp.parallel(build, watchFiles, browserSync);

exports.fontsStyle = fontsStyle;
exports.fonts = fonts;
exports.images = images;
exports.js = js;
exports.css = css;
exports.html = html;
exports.build = build;
exports.watch = watch;
exports.default = watch;