/*smartphones*/
@media (max-width: 767px) {

}

/*tablets portrait*/
@media (min-width: 768px) and (max-width: 991px) {

}

/*tablets landscape*/
@media (min-width: 992px) and (max-width: 1199px) {

}

Learning Resources

• Create a Responsive Web Design with Media Queries article.
• Optimizing Responsive Design Websites for Performance article.