Simplify build

package.json

@@ -3,38 +3,18 @@
   "version": "0.0.1",
   "private": true,
   "dependencies": {
-    "bootstrap": "4.1.3",
-    "jquery": "3.3.1",
-    "popper.js": "^1.14.4"
+    "bootstrap": "^4.3.1",
+    "jquery": "^3.2.1",
+    "popper.js": "^1.14.7"
   },
   "scripts": {
-      "build": "gulp"
+    "build": "sass --no-source-map --style=compressed app/main.scss app/main.css",
+    "watch": "sass --watch app/main.scss app/main.css"
   },
   "devDependencies": {
-    "browser-sync": "^2.24.6",
-    "connect": "^3.6.6",
-    "del": "^3.0.0",
-    "gulp": "^3.9.1",
-    "gulp-autoprefixer": "^5.0.0",
-    "gulp-csso": "^3.0.1",
-    "gulp-filter": "^5.1.0",
-    "gulp-flatten": "^0.4.0",
-    "gulp-if": "^2.0.2",
-    "gulp-imagemin": "^4.1.0",
-    "gulp-jshint": "^2.1.0",
-    "gulp-load-plugins": "^1.5.0",
-    "gulp-minify-css": "^1.2.4",
-    "gulp-plumber": "~1.2.0",
-    "gulp-sass": "~4.0.1",
-    "gulp-size": "^3.0.0",
-    "gulp-uglify": "^3.0.1",
-    "gulp-uncss": "^1.0.6",
-    "gulp-useref": "^3.1.5",
-    "jshint": "^2.9.6",
-    "jshint-stylish": "^2.2.1",
-    "opn": "^5.3.0"
+    "sass": "^1.20.1"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=10"
   }
 }