.challenge-section {
    padding: 100px 5%;
    background-color: var(--bg-color); /* Typically #F8F9FA or white */
    display: flex;
    justify-content: center;
}

.challenge-container {
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: 60px;
}

.challenge-content {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.challenge-title {
    font-size: 2.8rem;
    line-height: 1.2;
    color: var(--text-muted); /* Gray text for the first line */
    margin-bottom: 40px;
    font-weight: 600;
}

.challenge-title strong {
    color: var(--text-color); /* Darker text for "Harder" */
    font-weight: 700;
    font-size: 3rem;
}

.challenge-list {
    display: flex;
    flex-direction: column;
}

.challenge-item {
    display: flex;
    align-items: center;
    gap: 24px;
    padding: 24px 32px;
    border-bottom: 1px solid var(--border-color); /* Subtle divider */
    transition: all 0.3s ease;
    cursor: pointer;
}

.challenge-item:last-child {
    border-bottom: none;
}

.challenge-item.active {
    background-color: var(--card-bg); /* White background in light mode */
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.06); /* Shadow */
    border-bottom: 1px solid transparent;
    border-radius: 4px;
    /* Overhang active item */
    margin: -4px -16px;
    padding: 32px 48px; /* Bigger padding for active */
    z-index: 2;
    position: relative;
}

.challenge-icon {
    font-size: 28px;
    color: var(--text-muted); /* Dark gray */
}

.challenge-item.active .challenge-icon {
    color: var(--text-color);
}

.challenge-item p {
    font-size: 1.15rem;
    color: var(--text-muted); /* Gray text */
    margin: 0;
    line-height: 1.6;
    font-weight: 400;
}

.challenge-item.active p {
    color: var(--text-color); /* Darker text for active */
    font-weight: 500;
}

.challenge-visual {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: stretch;
}

.challenge-image {
    width: 100%;
    max-width: 500px;
    height: auto;
    border-radius: 20px;
    object-fit: cover;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.08);
}

/* Responsive adjustments */
@media (max-width: 992px) {
    .challenge-container {
        flex-direction: column;
        gap: 40px;
    }

    .challenge-visual {
        order: -1; /* optionally put image on top for mobile */
    }

    .challenge-title {
        font-size: 2.5rem;
        margin-bottom: 30px;
    }
    
    .challenge-item {
        padding: 24px 16px;
    }

    .challenge-item.active {
        margin: -5px -10px;
        padding: 24px;
        transform: scale(1.01);
    }
}

@media (max-width: 768px) {
    .challenge-title {
        font-size: 2.2rem;
    }
    
    .challenge-item p {
        font-size: 1rem;
    }
}