#contenedor_total {
     height: 100%;
 }

 #contenedor_imagen {
     height: 100vh;
     display: flex;
 }

 .item_flex {
     width: 100%;
     object-fit: cover;
 }

 .item_flex:hover {
     opacity: 0.8;
 }

 html, body {
     margin: 0;
 }

 @media screen and (max-width:600px) {
     #contenedor_imagen {
         display: block;
     }
 }