css when screen is smaller than code example
Example 1: css media screen
@media (max-width: 991px){
.mobile{
display: block;
}
}
Example 2: css if screen size less than
@media (max-width:960px) { css... } //nothing with screen size bigger than 960px
@media (min-width:960px) { css... } //nothing with screen size smaller than 960px