fix desync between index and 404 page

404.html

@@ -66,6 +66,9 @@
     span {
       text-align: center;
     }
+    a {
+      color: rgb(50, 100, 255);
+    }
     .title {
       font-size: 2.5em;
     }
@@ -99,7 +102,6 @@
       text-align: center;
     }
     #output-link {
-      color: rgb(50, 100, 255);
       word-break: break-all;
     }
     #output-ratio {
@@ -127,6 +129,10 @@
     #query-warning summary {
       cursor: pointer;
     }
+    header {
+      position: absolute;
+      top: 20px;
+    }
   </style>
   <script src="/qrcode.js"></script>
 </head>
@@ -134,6 +140,12 @@
 
   <div id="loader"></div>
 
+  <header>
+    <a class="source-link" href="https://github.com/p2r3/ha.mr" target="_blank">Source code on GitHub</a>
+    |
+    <a class="source-link" href="https://youtu.be/TOr1Vvji6jA" target="_blank">Explanation video</a>
+  </header>
+
   <div id="content">
 
     <h1 class="title">ha.mr</h1>
@@ -173,12 +185,6 @@
       <input type="checkbox" id="settings-qr" name="settings-qr" autocomplete="off">
       <label for="settings-qr"> Output QR code</label><br>
     </span>
-    <br><br>
-    <div>
-      <a class="source-link" href="https://github.com/p2r3/ha.mr">Source code on GitHub</a>
-      |
-      <a class="source-link" href="https://www.youtube.com/watch?v=TOr1Vvji6jA">Explanation video</a>
-    </div>
 
   </div>