fix sign buttons inconsistencies in the header

src/app/components/sign-in.tsx

@@ -21,10 +21,7 @@ export default function SignIn() {
   if (session?.user) {
     return (
       <div className="flex items-center gap-4">
-        <span className="text-sm text-muted-foreground hidden sm:inline">
-          {session.user.name || session.user.email}
-        </span>
-        <Button onClick={handleSignOut} variant="ghost" size="sm">
+        <Button onClick={handleSignOut} variant="ghost" size="default">
           Sign Out
         </Button>
       </div>
@@ -35,7 +32,7 @@ export default function SignIn() {
     <Button
       onClick={() => router.push("/auth/signin")}
       variant="outline"
-      size="sm"
+      size="default"
     >
       Sign In
     </Button>