/* Responsive Ad Placeholders */
.ad-placeholder {
    background: #f5f5f5;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    border-radius: 4px;
}

.ad-text {
    color: #666;
    font-weight: 500;
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Mobile: 320x100 */
.ad-placeholder {
    width: 320px;
    height: 100px;
}

/* Tablet: 468x60 */
@media (min-width: 768px) {
    .ad-placeholder {
        width: 468px;
        height: 60px;
    }
}

/* Desktop: 728x90 */
@media (min-width: 1024px) {
    .ad-placeholder {
        width: 728px;
        height: 90px;
    }
}