1. main.css

/*==================================================
=            Bootstrap 3 Media Queries             =
==================================================*/
 
/*==========  Mobile First Method  ==========*/
 
/* Large Devices, Wide Screens */
@media only screen and (max-width : 1200px) {
 
}
 
/* Medium Devices, Desktops */
@media only screen and (max-width : 992px) {
 
}
 
/* Small Devices, Tablets */
@media only screen and (max-width : 768px) {
 
}
/* Mobile L Devices, Phones */ 
@media only screen and (max-width : 480px) {
 
}
 

 /* Mobile M */ 
@media only screen and (max-width :375px ) {
    
}

/*Mobile S*/
@media only screen and (max-width : 320px) {
    
}