body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #fafafa;
    color: #222;
}

nav {
    background: white;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
}

nav h1 {
    margin: 0;
    font-size: 1.4rem;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 1.5rem;
    margin: 0;
    padding: 0;
}

nav ul li {
    cursor: pointer;
    padding: 0.5rem;
    transition: 0.3s ease;
}

nav ul li.active {
    border-bottom: 2px solid black;
    font-weight: bold;
}

section {
    display: none;
    padding: 3rem 4rem;
    max-width: 800px;
    margin: auto;
}

section.active {
    display: block;
}

h2 {
    margin-top: 0;
}