.spinner {
    border: 1em solid silver;
    border-top: 1em solid #337AB7;
    border-radius: 50%;
    width: 5em;
    height: 5em;
    animation: spin 700ms linear infinite;
    top: 40%;
    left: 55%;
    position: absolute;
    color: #00B050;
}

    .containerqrcode #content2 {
        border: dashed 2px #CCC;
        padding: 10px;
    }

Blazor-----Drag-----and-----Drop-----CSS

    .drag-drop-zone:hover {
        background-color: #f5f5f5;
    }

    .drag-drop-zone input[type=file] {
        position: absolute;
        width: 100%;
        height: 100%;
        opacity: 0;
        cursor: pointer;
    }

@media (max-width: 767.98px){
    .languages {
        margin-left: 0em;
    }

    .containerqrcode {
        margin: auto;
        color: darkblue;
    }

    .imgqrcode {
        width: 19em;
    }

    .companyImg {
        margin-top: 1em;
        margin-left: 1em;
        width: 17em;
    }

    .imgBS {
        margin: 0;
    }

    .coreSteps {
        font-size: 70%;
        font-weight: 400;
    }

    .demo-card {
        max-width: 380px;
    }

    .hauteur {
        height: 17em;
    }

    .page-footer {
        position: sticky;
        margin-top: 6em;
    }
}

@media (min-width: 768px) {
    .languages {
        margin-left: 2em;
    }

    .containerqrcode {
        width: 800px;
        margin: auto;
        color: darkblue;
        font-size: 20px;
    }

    .imgqrcode {
        width: 25em;
    }

    .companyImg {
        margin-top: 2em;
        margin-left: 1em;
        width: 17em;
    }

    .imgBS {
        margin: 2em 0em 0em 0em;
    }

    .coreSteps {
        font-size: 80%;
        font-weight: 400;
    }

    .demo-card {
        max-width: 800px;
    }

    .hauteur {
        height: 12em;
    }

    .page-footer {
        position: sticky;
        margin-top: 10em;
    }

    .statistics {
        margin-left: 62px;
    }
}

.card-border {    
    border: 1px dashed #00B050;
    border-radius: 6%;
}

.drag-drop-zone {
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #eee;
    box-shadow: inset 0 0 8px rgba(0,0,0,0.2);
    color: #aeaeae;
    font-size: 1rem;
    cursor: pointer;
    margin: 1rem;
    position: relative;
}