.ad-section {
    background-color: #ffffff;
    padding: 40px 0; /* 上下40px、左右0 */
    /* padding: 40px 0 0 0; この行を削除して下の余白を確保 */
}

.ad-container {
    display: flex;
    justify-content: center;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.ad-banner {
    width: 350px;
    height: 350px;
    display: block;
    transition: opacity 0.3s ease;
}

.ad-banner:hover {
    opacity: 0.8;
}

@media (max-width: 768px) {
    .ad-banner {
        width: 100%;
        height: auto;
        max-width: 500px;
    }
}