/* Demo-Button dieses Tutorials (nur diese Seite) */
.tu-article a.btt-demo{ text-decoration:none;

  position:fixed; left:30px; bottom:30px; z-index:900;
  padding:12px 18px; border-radius:6px; font-weight:700;
  background:var(--red); color:var(--white); border:1px solid var(--red);
  opacity:0; pointer-events:none; transform:translateY(10px);
  transition:opacity .3s ease, transform .3s ease, background .2s ease;
}
.tu-article a.btt-demo.is-visible{ opacity:1; pointer-events:auto; transform:none; }
.tu-article a.btt-demo:hover, .tu-article a.btt-demo:focus-visible{ background:var(--red-deep); color:var(--white); }