Improve accessibility and polish page styling

components/Game.tsx

@@ -192,7 +192,7 @@ export function Game({ id }: { id: string }) {
   const total =
     session?.rounds.reduce((n, r) => n + (r.result?.score || 0), 0) || 0;
   return (
-    <main className="game-page">
+    <main className="game-page" id="main-content" tabIndex={-1}>
       {session && current && (
         <Panorama
           key={session.round}

components/MultiplayerRoom.tsx

@@ -167,7 +167,7 @@ export function MultiplayerRoom({ id }: { id: string }) {
           {t("Play & maps")}
         </Link>
       </header>
-      <main className="section page-content multiplayer-lobby">
+      <main className="section page-content multiplayer-lobby" id="main-content" tabIndex={-1}>
         {error && (
           <p className="error-message" role="alert">
             {t(error)}{" "}

components/PageLoading.tsx

@@ -7,6 +7,8 @@ export async function PageLoading() {
       className="section page-content route-loading"
       aria-busy="true"
       aria-label={t("Loading page")}
+      id="main-content"
+      tabIndex={-1}
     >
       <p role="status" className="muted">
         {t("Loading page")}…