.container {

    margin: 20px auto 50px auto;
    width: 50%;
    
    
}
header {
    margin: 50px auto 50px auto;
    width: 50%;
    text-align: center;
   
}
body{
    background-image: url(1.jpg);
    background-repeat: no-repeat;
    background-size: cover;
    }