.container_quaderno {
  width: 100%;
  height: 100%;
  /* Usa un grigio appena percettibile per le linee del quaderno */
  --color: rgba(255, 255, 255, 0.05); 
  
  /* Usa la variabile globale del tema per lo sfondo! */
  background-color: var(--bg-color) !important;
  
  background-image: linear-gradient(
      0deg,
      transparent 24%,
      var(--color) 25%,
      var(--color) 26%,
      transparent 27%,
      transparent 74%,
      var(--color) 75%,
      var(--color) 76%,
      transparent 77%,
      transparent
    ),
    linear-gradient(
      90deg,
      transparent 24%,
      var(--color) 25%,
      var(--color) 26%,
      transparent 27%,
      transparent 74%,
      var(--color) 75%,
      var(--color) 76%,
      transparent 77%,
      transparent
    ) !important;
  background-size: 55px 55px !important;
}