improved dev experience, fixed css order

client/coral-admin/src/components/App.css

@@ -0,0 +1,9 @@
+html, body, #root, #root > div {
+  min-height: 100%;
+}
+
+body {
+  margin: 0;
+  background-color: #FAFAFA;
+  font-family: 'Roboto', sans-serif;
+}

client/coral-admin/src/components/App.js

@@ -1,5 +1,6 @@
 import React from 'react';
 import ToastContainer from './ToastContainer';
+import './App.css';
 import 'material-design-lite';
 
 import AppRouter from '../AppRouter';