*,
*::before,
*::after
{
    box-sizing: border-box;
}

html,
body
{
    font-family: system-ui, sans-serif;
    font-size: 1rem;
    background-color: #f1f1f1;
    color: #333;
    margin: 0;
    padding: 0;
}

header,
nav,
main,
footer
{
    margin-left: auto;
    margin-right: auto;
    padding: 1rem;
    background-color: #fff;
}

header,
footer
{
    background-color: #3399ff;
    color: #fff;
}

nav
{
    background-color: #66b3ff;
    color: #fff;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

nav a
{
    color: #fff;
    text-decoration: none;
    text-align: center;
}

nav a:hover
{
    text-decoration: underline;
}

nav a.current
{
    font-weight: bold;
}

@media( min-width: 800px )
{
    html,
    body
    {
        margin: 1rem 0;
        padding: 0;
    }
    
    header,
    nav,
    main,
    footer
    {
        max-width: 85%;
    }
    
    header
    {
        border-radius: 1rem 1rem 0 0;
    }
    
    footer
    {
        border-radius: 0 0 1rem 1rem;
    }
    
    nav
    {
        flex-direction: row;
    }
}