html,
body {
    height: 100%;
    margin: 0;
    padding: 0;
    background: #fff;
    color: #000;
    font-family: 'Courier New', Courier, monospace;
}

header {
    width: 100%;
    background: #fff;
    border-bottom: 1px solid #000;
    padding: 0.5em 0;
}

nav {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2em;
}

nav a {
    color: #000;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.1em;
    transition: color 0.2s;
    /* Add box styling */
    border: 2px solid #000;
    border-radius: 6px;
    padding: 0.3em 1em;
    background: #f5f5f5;
    box-shadow: 1px 1px 4px #ddd;
    margin-bottom: 0.1em;
}

nav a:hover {
    color: #555;
    background: #e0e0e0;
    border-color: #555;
}

nav a.selected {
    background: #cce5ff;
    border-color: #339af0;
    color: #003366;
}

main {
    max-width: 1000px;
    margin: 2em auto;
    padding: 0 1em;
}

@media (max-width: 1000px) {
    nav {
        flex-direction: column;
        gap: 1em;
    }

    main {
        margin: 1em auto;
    }
}