add functional to header

script.js

@@ -0,0 +1,12 @@
+const navigationItems = document.querySelectorAll(".nav__item");
+
+navigationItems.forEach((item) => {
+  item.onclick = (elem) => {
+    navigationItems.forEach((item2) =>
+      item2.classList.remove("nav__item_active")
+    );
+
+    !item.classList.contains("nav__item_active") &&
+      item.classList.add("nav__item_active");
+  };
+});