_layout.scss

// Layout

*,
*:before,
*:after {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}
@mixin size($size) {
  @if $size == sm {
    @media (min-width: 415px) {
      @content;
    }
  }
  @else if $size == md {
    @media (min-width: 668px) {
      @content;
    }
  }
  @else if $size == lg {
    @media (min-width: 769px) {
      @content;
    }
  }
  @else if $size == xl {
    @media (min-width: 1025px) {
      @content;
    }
  }
}