How to put a banner on the rich text background ?

hello, i have a pb i am trying to put a banner behind my rich text background, i tried everything but i cannot have the banner fully adapt to the size of the computer or mobile version automatically, there is always a black square around (check ss), my link : https://mobilegear.fr/

I tried this code in section-rich-text-css i changed a lot of things but i have always this square i would like to have the same wide background as my newsletter :

.rich-text__wrapper {
background-image: url(‘https://cdn.shopify.com/s/files/1/0822/3775/1645/files/Design_sans_titre_15.jpg?v=1711476126’);
background-repeat: no-repeat;
background-size: cover;
background-position: center;
padding-top: 30px; /* Ajustez la marge supérieure si nécessaire /
padding-bottom: 30px; /
Ajustez la marge inférieure si nécessaire */
}

.rich-text__blocks {
padding: 0; /* Supprimer les marges internes */
}

.rich-text__blocks h1 {
font-size: 2rem; /* Taille du titre h1 /
font-weight: bold; /
Mettre le titre h1 en gras */
}

@media only screen and (max-width: 768px) {
.rich-text__blocks h1 {
font-size: 1.5rem; /* Ajuster la taille du titre h1 pour les appareils mobiles */
}
}