style(web): use 3:4 aspect ratio for viewers

apps/web/src/components/viewers/PdfViewer.tsx

@@ -36,7 +36,7 @@ export default function PdfViewer({ object }: { object: TTSObject }) {
       <iframe
         src={proxied}
         title="PDF preview"
-        className="h-[70vh] w-full rounded-lg border border-zinc-800 bg-zinc-950"
+        className="aspect-[3/4] w-full rounded-lg border border-zinc-800 bg-zinc-950"
       />
     </div>
   );

apps/web/src/components/viewers/Scene.tsx

@@ -57,7 +57,7 @@ export default function Scene({
   return (
     <div
       ref={containerRef}
-      className="relative h-80 w-full overflow-hidden rounded-lg bg-linear-to-b from-zinc-300 to-zinc-400"
+      className="relative aspect-[3/4] w-full overflow-hidden rounded-lg bg-linear-to-b from-zinc-300 to-zinc-400"
     >
       <LoadingOverlay />
       {fullscreen && (