header{
    background-color: blue;
    padding: 10px;
    text-align: center;
    position: fixed;
    width: 100%;
    z-index: 1;
    top: 0;
    left: 0;
}
header h1{
    color: white;
    border: 8px solid white;
    padding: 6px 12px;
    display: inline-block;
    border-radius: 35px;
}
main{
    position: sticky;
    top: 160px;
    margin: 0;
    padding: 0;
}
main img{
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
}

main button{
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
}