elf-notes/sass/design/_breakpoints.scss

$breakpoints:
    540px 576px,  
    720px 768px,
    960px 992px,
    1140px 1200px,
    1320px 1400px;

.container {
  min-width: 320px; 

  @each $max, $bp in $breakpoints {
    @media (min-width: $bp) {
      max-width: $max;
    }
  }
}