body {
    text-align: center;
}
.backgr { 
    background-color: #474e5d;
    color: #ffffff;
    font-size: 20px;
}
.container-fluid {
    padding-top: 35px;
    padding-bottom: 35px;
}
.btn {
    width: 200px;
    background-color: #596473;
}
.mySlides{
    margin: auto;
    width: 800px;
    height: 450px;
}