feat(appearance): accent color, corners, wide layout and game art background

src/components/PageBackground.jsx

@@ -0,0 +1,21 @@
+import {useState} from 'react';
+import {coverUrl, heroUrl} from '../utils/games.js';
+
+/**
+ * Game art behind the whole page, blurred and dimmed so text on it stays readable. Falls back to the store
+ * header for apps without library art. Give it `key={appid}`, so a new game starts with its library art again.
+ */
+export default function PageBackground({appid}) {
+    const [failures, setFailures] = useState(0);
+
+    if (!appid || failures > 1) return null;
+
+    return (
+        <div aria-hidden="true" className="pointer-events-none fixed inset-0 -z-10 overflow-hidden">
+            <img src={failures === 0 ? heroUrl(appid) : coverUrl(appid)} alt=""
+                 onError={() => setFailures((count) => count + 1)}
+                 className="size-full scale-110 object-cover blur-md"/>
+            <div className="absolute inset-0 bg-background/80"/>
+        </div>
+    );
+}