Responsive centered single column page by scss

layout.scss

body {
  font-size: 18px;
  margin 0 auto;
  
  @media screen and (max-width: 1040px){
    font-size: 16px;
    width: 60%;
  }
    
  @media screen and (max-width: 600px){
    font-size: 14px;
    width: 80%;
  }
}