fix: stickers and chat UI fix

components/chat/shared-post-card.tsx

@@ -19,7 +19,7 @@ export function SharedPostCard({ attachment }: { attachment: Attachment }) {
 
   if (!post || attachment.entity_unavailable) {
     return (
-      <div className="flex items-center gap-2 rounded-lg border border-border bg-muted/30 px-3 py-2.5">
+      <div className="flex w-full items-center gap-2 rounded-lg border border-border bg-muted/30 px-3 py-2.5 sm:max-w-64">
         <ImageOff className="size-4 shrink-0 text-muted-foreground" aria-hidden />
         <span className="text-sm text-muted-foreground">
           This post is no longer available
@@ -31,7 +31,11 @@ export function SharedPostCard({ attachment }: { attachment: Attachment }) {
   return (
     <Link
       href={`/u/${encodeURIComponent(post.author_handle)}/posts#post-${post.id}`}
-      className="block overflow-hidden rounded-lg border border-border bg-card transition-colors hover:bg-muted/40"
+      // Capped on wide screens. The bubble allows 78% of the column, which on
+      // a phone is a sensible ~265px but on desktop is over 500px — and with
+      // a square image that makes a shared post taller than the viewport.
+      // Mobile keeps the bubble's own width; only sm+ needs the ceiling.
+      className="block w-full overflow-hidden rounded-lg border border-border bg-card transition-colors hover:bg-muted/40 sm:max-w-64"
     >
       <span className="flex items-center gap-2 px-3 py-2">
         <UserAvatar