#upload img.preview_picture {
    max-height: 25rem;
    margin: 0 auto;
    display: block;
}

#upload div.drop {
    height: 25rem;
    width: 100%;
    background-color: red;
}

#upload img.preview_picture {
    max-height: 25rem;
    max-width: calc(100% - 4rem);
    margin: 0 auto;
    display: block;
}

#upload div.drop {
    height: 25rem;
    width: 100%;
    background-color: red;
}

Set a max-width for the picture preview in Upload
Set a max-width for the picture preview in Upload
