html,
body {
    margin: 0;
    padding: 0;
    font-weight: 600;
    background-image: url(Image/codex.gif);
    height: 100%;
    font-size: 24px;
}

.message-container {
    display: flex;
    justify-content: center;
    margin-top: 10px;
}

#message {
    color: green;
    font-weight: bold;
    background-color: black;
    padding: 5px;
    font-size: 20px;
}

.container {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
    flex-direction: column;
}


header {
    background-color: black;
    font-size: 64px;
    color: green;
    display: flex;
    justify-content: center;
    padding: 2px;
}

.flexing {
    display: flex;
    justify-content: space-between;
    margin: 5px;
}

.child {
    background-color: green;
    padding: 5px;
    margin: 5px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    width: 400px;
}

button {
    background-color: black;
    color: green;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 5px;
    font-weight: 600;
}

.output {
    width: 200px
}

input {
    background-color: black;
    color: green;
    text-align: center;
    padding: 2px;
}

@media (max-width:576px) {

    html,
    body {
        font-size: 16px;
    }

    header {
        font-size: 32px;
    }

    .child {
        width: 300px;
    }
}

@media (min-width:768px) {
    header {
        font-size: 64px;
    }

    .container {
        height: 85%;
    }

    .output {
        width: 320px;
    }
}