body::before{
    content: "";
    background-image: url(imagenespoli/Bandera_de_España.webp);
    background-size: cover;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0.3; 
    z-index: 0;
   
}
body{
    
}
h1{
    opacity: 1;
}
img{
    opacity: 1;
}