Add header and logo; set dark theme up

src/App.vue

@@ -1,6 +1,9 @@
 <template>
   <div id="app">
-    <img alt="Vue logo" src="./assets/logo.png">
+    <div>
+      This is the (extremely early alpha of the) new Feast. If you're looking for the old version, <a href="https://classic.feast.crux.sexy">go here!</a>
+    </div>
+    <img alt="Feast logo" id="logo" src="./assets/feast.png">
     <Combat :player="player" :enemy="enemy" />
   </div>
 </template>
@@ -30,12 +33,20 @@ export default class App extends Vue {
 </script>
 
 <style>
+body, html {
+  background: #111;
+}
+
 #app {
   font-family: Avenir, Helvetica, Arial, sans-serif;
   -webkit-font-smoothing: antialiased;
   -moz-osx-font-smoothing: grayscale;
   text-align: center;
-  color: #2c3e50;
+  color: #ddd;
+  background: #111;
   margin-top: 60px;
 }
+#logo {
+  width: 30vw;
+}
 </style>