.btn-file {
    position: relative;
    overflow: hidden;
}

.btn-file input[type=file] {
    position: absolute;
    top: 0;
    right: 0;
    min-width: 100%;
    min-height: 100%;
    font-size: 100px;
    text-align: right;
    filter: alpha(opacity=0);
    opacity: 0;
    outline: none;
    background: white;
    cursor: inherit;
    display: block;
}

.img-zone {
    background-color: #F2FFF9;
    border: 5px dashed #4cae4c;
    border-radius: 5px;
    padding: 20px;
}

.img-zone h2 {
    margin-top: 0;
}

.progress, #img-preview {
    margin-top: 15px;
}