css mobile only rules code example
Example: media query in html style
span { background-image: url(particular_ad.png); }
@media (max-width: 300px) {
span { background-image: url(particular_ad_small.png); }
}
span { background-image: url(particular_ad.png); }
@media (max-width: 300px) {
span { background-image: url(particular_ad_small.png); }
}