Sass (SCSS) mixin for easy media query breakpoint managing

The mixin I currently use for breakpoints. Breakpoints are defined in PXs, because it's easier to read for humans. But they are converted to EMs, because they provide more consistency between different browsers. ( See this study: http://zellwk.com/blog/media-query-units/)

how to use

Define your breakpoints in px

$breakpoints: 480 640 800 960 1200 1480 1840 2080;

Copy the file into the folder where your main-scss-file is. Include this file in your main-scss-file like this:

@import 'breakpoints';

The function:

@mixin brp($name) {
	@for $i from 1 through length($breakpoints) {
		$px_value: nth($breakpoints, $i);

		@if $name == 'b'+$i {
			@media all and (min-width: #{$px_value/16}em) {
				@content;
			}
		}
		@if $name == 'b'+$i+'max' {
			@media all and (max-width: #{$px_value/16 - 0.062}em) {
				@content;
			}
		}
	}
}

Now you can do e.g.:

body {
	@include brp(b2max) {
		background-color:green;
	}
	@include brp(b4) {
		background:red;
	}
}

...which translates to:

@media all and (max-width: 39.937em) {
	body {
		background-color: green;
	}
}

@media all and (min-width: 60em) {
    body {
      background: red;
  	}
}