* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;

    display: flex;
    flex-direction: column;

    font-family: Arial, sans-serif;
}

header {
    padding: 20px;
    background: #222;
    color: white;
}

main {
    flex: 1;

    display: flex;
    justify-content: center;
    align-items: center;
}

footer {
    padding: 20px;
    background: #222;
    color: white;
    text-align: center;
}