frontend: Preloader & 404 Error page

frontend/public/css/general.css

@@ -45,6 +45,26 @@ a:hover {
     align-items: center;
 }
 
+/* LOADING */
+.isLoading {
+    display: none;
+}
+#preloader {
+    min-height: 100vh;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+}
+@keyframes Loader__spin {
+    0% {
+        animation-timing-function: cubic-bezier(0.5856, 0.0703, 0.4143, 0.9297);
+        transform: rotate(0deg);
+    }
+    100% {
+        transform: rotate(360deg);
+    }
+}
+
 /* UTILITIES */
 .text-center {
     text-align: center;

frontend/public/css/pages/404.css

@@ -0,0 +1,7 @@
+.Error404__container {
+    display: flex;
+    flex-direction: column;
+    justify-content: center;
+    align-items: center;
+    min-width: 100%;
+}

frontend/public/js/preloader.js

@@ -0,0 +1,4 @@
+window.addEventListener('load', () => {
+    document.querySelector('.isLoading').classList.remove('isLoading');
+    document.getElementById('preloader').remove();
+});