body {
    background-color: #f8f9fa;
}

.card {
    border: none;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.level-card {
    transition: transform 0.2s ease-in-out, box-shadow 0.2s ease-in-out;
    border-radius: .5rem;
    overflow: hidden;
}

.level-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
}

.level-link {
    text-decoration: none;
    color: inherit;
}

.level-locked {
    position: relative;
    cursor: not-allowed;
}

.level-locked img {
    filter: grayscale(100%);
    opacity: 0.7;
}

.locked-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.3);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    color: rgba(0, 0, 0, 0.4);
}

.level-locked .card-body {
    background-color: #f8f9fa;
}

/* FontAwesome Lock Icon - requires adding FontAwesome kit to the HTML */
@import url('https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.4/css/all.min.css');