.challenge-card.completed {
    position: relative;
    filter: grayscale(100%);
    opacity: 0.7;
    --pointer-events: none;
}

.completed-overlay {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: rgba(0, 200, 100, 0.85);
    color: white;
    padding: 10px;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 700;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
}

.new-badge {
    background: #ff4a4a;
    color: white;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: capitalize;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.6; }
}

.completion-stat {
    font-size: 1.1rem;
    color: #666;
    margin-top: 10px;
}

.stat-beginner {
    color: #00b87a;
    font-weight: 700;
}

.stat-novice {
    color: #d9a000;
    font-weight: 700;
}

.stat-advanced {
    color: #ef476f;
    font-weight: 700;
}

.stat-expert {
    color: #9b59b6;
    font-weight: 700;
}