body {
    font-family: 'Arial', sans-serif;
    background-color: #e9f7ef;
}

.custom-navbar {
    background-color: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(10px);
}

.card {
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
}

footer {
    margin-top: auto;
}

.challenge-card {
    margin-bottom: 20px;
}

.challenge-title {
    font-size: 1.5rem;
}

.challenge-description {
    font-size: 1rem;
}

.btn-success {
    background-color: #28a745;
    border-color: #28a745;
}

.btn-success:hover {
    background-color: #218838;
}

#refresh-btn {
    background-color: #007bff;
}

#refresh-btn:hover {
    background-color: #0056b3;
}