keyboard-driven navigation

Resolves #66

js/src/features/particles/particle-preview.tsx

@@ -37,7 +37,7 @@ function TextPreview({ particle }: { particle: Extract<Particle, { type: "text"
       : particle.properties.content;
   return (
     <div className="flex h-full w-full items-center justify-center p-4">
-      <p className="line-clamp-4 text-center text-4xl leading-relaxed">
+      <p className="line-clamp-4 text-center text-xl leading-relaxed">
         {truncated}
       </p>
     </div>
@@ -100,7 +100,7 @@ function VideoThumbnail({
   }
 
   return (
-    <div className="relative h-full w-full bg-black">
+    <div className="relative h-full w-full bg-black blur-[2px]">
       <video
         src={`${url}#t=2`}
         preload="metadata"