Fixed a typo on the offline page

Author: splamei

public/offline.html

@@ -49,7 +49,7 @@
         onerror="this.style.display='none'"
       />
       <div>
-        Sorry, you appears to be offline. <br />The game requires an internet
+        Sorry, you appear to be offline. <br />The game requires an internet
         connection to work :(
       </div>
       <div