body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 20px;
    background-color: #f4f4f4;
}

article {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

header h1 {
    font-size: 2em;
    margin-bottom: 0.5em;
}

header p {
    color: #888;
    margin-bottom: 1em;
}

section p {
    line-height: 1.6;
    margin-bottom: 1em;
}

footer p {
    font-style: italic;
    color: #555;
}

header.fake-header {
    display: none;
}

.clickable-text {
    color: blue;
    text-decoration: underline;
    cursor: pointer;
}

.invisible {
    display: none;
}

.main-nav {
    background-color: #333;
    padding: 1em;
    margin-bottom: 20px;
}

.main-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: center;
    gap: 2em;
}

.main-nav li {
    margin: 0;
}

.main-nav a {
    color: white;
    text-decoration: none;
    padding: 0.5em 1em;
    border-radius: 4px;
    transition: background-color 0.3s;
}

.main-nav a:hover {
    background-color: #555;
}

.main-nav a.active {
    background-color: #555;
}