title: Bootstrap 4 grid-only css, using bootstrap media queries in my scss style
body: <p>I'm pretty much new to Bootstrap 4 and Sass\SCSS,I wanted to use the new grid and style the rest of my website on my own using SCSS, so I downloaded bootstrap source, compiled bootstrap-grid.scss (which is only the grid plus some variables and mixins), now the question that pops in my mind is : How do I use bootstrap's media queries screen sizes with my own style? Is there a particular mixin/way to call the breakpoints? Or since I'm using the grid only I have to configure media queries myself? </p>
  
  <p>My idea was that there probably would be a mixin that allows me to do for example :</p>
  
  <pre><code>.my_class {
    color: red;
    +mobile {
    color: blue;
    }
  }
  </code></pre>
  
  <p>Does bootstrap have something like this? I have to do it on my own? How do you proceed when working with the grid only?</p>