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

header {
    background-color: #004080;
    color: white;
    text-align: center;
    padding: 30px 20px;
}

header h1 {
    margin: 0;
    font-size: 2.8em;
}

.banner-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.content {
    max-width: 900px;
    margin: 40px auto;
    padding: 0 20px;
}

.content h2 {
    background-color: #e0ecf8;
    color: #004080;
    font-size: 1.6em;
    padding: 10px 15px;
    border-radius: 5px;
    margin-top: 40px;
}

.content p {
    font-size: 1.1em;
    line-height: 1.7em;
    margin-bottom: 20px;
}

.back-link,
.learn-more {
    display: inline-block;
    color: #004080;
    font-weight: bold;
    text-decoration: none;
}

.back-link {
    margin-bottom: 25px;
}

.learn-more {
    margin-top: 10px;
    margin-bottom: 25px;
}

.back-link:hover,
.learn-more:hover {
    text-decoration: underline;
}

.challenge-image {
    display: block;
    width: 100%;
    max-width: 900px;
    height: auto;
    margin: 25px auto;
    border-radius: 8px;
}

footer {
    background-color: #004080;
    color: white;
    text-align: center;
    padding: 20px;
    margin-top: 50px;
}

/* Main navigation bar */
.main-nav {
    background-color: #e0ecf8;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    border-bottom: 1px solid #c5d8eb;
}
.main-nav a {
    color: #004080;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.05em;
    padding: 14px 20px;
    transition: background-color 0.2s ease, color 0.2s ease;
}
.main-nav a:hover {
    background-color: #004080;
    color: white;
}
@media (max-width: 650px) {
    .main-nav a { padding: 11px 12px; font-size: 0.95em; }
}