html,body{
    margin: 0;
    padding: 0;
    border-radius: 0px;
}

@media (prefers-color-scheme: light){
    .header{
        background-color: #fff;
        color: #000;
    }
}

@media (prefers-color-scheme: dark){
    .header{
        background-color: #000;
        color: #fff;
    }
}