*{
    margin:0;
    padding:0;
    box-sizing:border-box;
}

html,
body{
    width:100%;
    height:100%;
    background:#f3f3f3;
}

body{
    display:flex;
    justify-content:center;
    align-items:flex-start;
}

.placeholder{
    width:100%;
}

.placeholder picture,
.placeholder img{
    display:block;
    width:100%;
    height:auto;
}

/*
    Desktop:
    Originalgrafik vollständig anzeigen
*/

@media (min-width:769px){

    .placeholder{
        max-width:1920px;
        margin:0 auto;
    }

    .placeholder img{
        width:100%;
        height:auto;
    }
}

/*
    Mobile:
    Mobile-Grafik verwenden
*/

@media (max-width:768px){

    .placeholder{
        width:100%;
    }

    .placeholder img{
        width:100%;
        height:auto;
    }
}