Simple media queries 
This repository contains SCSS-mixins which allow you to easily use media queries in SCSS. With this approach, you don't override previous defined code, but only target the desired screenrange.
The mixins
.selector {
// Include general theming here
@include down(600) {
// Theming for small screens here
}
@include between(600, 1200) {
// Theming for screens between 600px and 1200px here
}
@include up(1200) {
// Theming for big screens here
}
@include outside(600, 1200) {
// Theming for screens below 600px and above 1200px
}
}