Added a hamburger menu for the navbar

index.html

@@ -83,6 +83,10 @@
 
 	</div>
 	</div>
+
+	<button class="mobile-nav-toggle" aria-label="Toggle menu">
+	☰
+	</button>
 	
 	<nav class="navbar">
 	<div class="navbar-top-icons">