* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    color: #333;
    background: #fff;
    display: flex;
    flex-direction: column;
}

/* ---- Header / Menu ---- */

header {
    background: #2c3e50;
    padding: 0 1rem;
    flex-shrink: 0;
}

#menu {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem;
}

#menu li a {
    display: block;
    padding: 1rem 1.25rem;
    color: #ecf0f1;
    text-decoration: none;
    font-size: 1rem;
    transition: background 0.2s;
}

#menu li a:hover,
#menu li a:focus {
    background: #34495e;
}

/* ---- Main content ---- */

main {
    flex: 1 0 auto;
    padding: 2rem 1rem;
    max-width: 960px;
    width: 100%;
    margin: 0 auto;
}

/* ---- Footer ---- */

footer {
    flex-shrink: 0;
    background: #2c3e50;
    color: #bdc3c7;
    text-align: center;
    padding: 1rem;
    font-size: 0.875rem;
}

/* ---- Mobile adaptation ---- */

@media (max-width: 600px) {
    #menu {
        flex-direction: column;
        align-items: center;
    }

    #menu li a {
        width: 100%;
        text-align: center;
        padding: 0.75rem 1rem;
    }

    main {
        padding: 1.5rem 0.75rem;
    }
}