Added mobile first menu and started responsive

Swithced the main nav to a mobile layout to cut down on complex
responsive styling to make the heaader work.

Also began touching up site wide responsive styles so the site works on
multiple devices.

app/Http/Controllers/ExportController.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Http\Controllers;
+
+class ExportController extends Controller
+{
+    //
+    public function exportCSV()
+    {
+        /*
+        $columns = [
+            'id',
+            'product_name',
+            'product_url',
+            'price',
+            'category'
+        ];
+
+        $products = [
+            [1, 'product 1', 'https://example.com/product-1', '9.99', 'category 1'],
+            [2, 'product 2', 'https://example.com/product-2', '19.99', 'category 2'],
+            [3, 'product 3', 'https://example.com/product-3', '29.99', 'category 3'],
+            [4, 'product 4', 'https://example.com/product-4', '39.99', 'category 4'],
+        ];
+
+        header('Content-Type: text/csv');
+        header('Content-Disposition: attachment; filename="products.csv"');
+
+        echo implode(',', $columns) . PHP_EOL;
+        foreach ($products as $product) {
+            echo implode(',', $product) . PHP_EOL;
+        }
+        */
+    }
+}