IPython/frontend/html/notebook/static/css/alternateuploadform.css

/* We need an invisible input field on top of the sentense*/
/* "Drag file onto the list ..." */

.alternate_upload
{
    background-color:none;
    display: inline;
}

.alternate_upload.form
{
    padding: 0;
    margin:0;
}

.alternate_upload input.fileinput
{
    background-color:red;
    position:relative;
    opacity: 0;
    z-index: 2;
    width: 356px;
}