Media queries

HTML head

<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=1">

style.css

@media screen and (max-width:979px){
    ....
}

@media screen and (min-width:980px){
    ....
}

@media screen and (min-width:765px) and (max-width:980px){
    ....
}