Creating a WordPress theme that nudges authors towards SEO with CSS. Good idea or bad idea?

seo.scss

body.admin-bar .post-content h1 {
  border: 2px solid red;

  &:before {
    content: "Using H1 tags in post content is bad for SEO. Change to an H2 tag. (You're only seeing this because you're signed in as an admin. Your visitors won't see this warning)";
    background-color: red;
    color: white;
    font-size: 1rem;
    line-height: 1;
    padding: 1em;
    display: block;
  }
}