plane/apps/space/app/not-found.tsx

// assets
import SomethingWentWrongImage from "@/app/assets/something-went-wrong.svg?url";

function NotFound() {
  return (
    <div className="h-screen w-screen grid place-items-center">
      <div className="text-center">
        <div className="mx-auto size-32 md:size-52 grid place-items-center rounded-full bg-custom-background-80">
          <div className="size-16 md:size-32 grid place-items-center">
            <img src={SomethingWentWrongImage} alt="Something went wrong" width={128} height={128} />
          </div>
        </div>
        <h1 className="mt-8 md:mt-12 text-xl md:text-3xl font-semibold">That didn{"'"}t work</h1>
        <p className="mt-2 md:mt-4 text-sm md:text-base">
          Check the URL you are entering in the browser{"'"}s address bar and try again.
        </p>
      </div>
    </div>
  );
}

export default NotFound;