html{
    background-color: #555555;
}

body{
    background-color: white;
    width: 500px;
    margin: 20px auto;
    height: 500px;
    
}
div{
    width: 400px;
    height: 400px;
    border: 1px solid black;
    background-color: blue;
    text-align: center;
    border-radius: 200px;
    margin:  49px;
    display: inline-block;
}
button{
    width: 50px;
    height: 50px;
    background-color: crimson;
    text-align: 50px ;
    margin: 200px auto; ;

}