increase font size on mobile

src/layout/app.css

@@ -20,6 +20,15 @@
 
     body {
         font-family: sans-serif;
+        font-size: 18px;
+
+        @media screen and (min-width: 640px) {
+            font-size: 16px;
+        }
+    }
+
+    input {
+        font-size: 1em;
     }
 
     #appContainer {