Added favicons, re: #5.

public/_layout.jade

@@ -3,6 +3,13 @@ html
   head
     title= title
     meta(name="viewport" content="width=device-width, initial-scale=1")
+    meta(name="theme-color", content="#fff")
+    link(rel="apple-touch-icon", sizes="152x152", href="#{process.env.PROJECT_ROOT || '/'}img/favicons/apple-touch-icon.png")
+    link(rel="icon", type="image/png", sizes="32x32", href="#{process.env.PROJECT_ROOT || '/'}img/favicons/favicon-32x32.png")
+    link(rel="icon", type="image/png", sizes="16x16", href="#{process.env.PROJECT_ROOT || '/'}img/favicons/favicon-16x16.png")
+    link(rel="manifest", href="#{process.env.PROJECT_ROOT || '/'}img/favicons/site.webmanifest")
+    link(rel="mask-icon", href="#{process.env.PROJECT_ROOT || '/'}img/favicons/safari-pinned-tab.svg", color="#000")
+    link(rel="shortcut icon", href="#{process.env.PROJECT_ROOT || '/'}img/favicons/favicon.ico")
     link(rel="stylesheet" href="#{process.env.PROJECT_ROOT || '/'}css/main.css")
   body.sans-serif.tc.lh-copy.flex.flex-column.items-center.justify-around.vh-85.mh2
     != yield

public/img/favicons/site.webmanifest

@@ -0,0 +1,14 @@
+{
+    "name": "Barcode Generator",
+    "short_name": "Barcode Generator",
+    "icons": [
+        {
+            "src": "android-chrome-144x144.png",
+            "sizes": "144x144",
+            "type": "image/png"
+        }
+    ],
+    "theme_color": "#ffffff",
+    "background_color": "#ffffff",
+    "display": "standalone"
+}