$breakpoints: () !default
@function breakpoint($max-width: false, $min-width: false, $columns: false, $fallback-width: false)
$breakpoint: () @if $columns $breakpoint: join($breakpoint, columns $columns) @if $fallback-width $breakpoint: join($breakpoint, fallback-width $fallback-width) @if $max-width $breakpoint: join($breakpoint, max-width $max-width) @if $min-width $breakpoint: join($breakpoint, min-width $min-width) $breakpoints: append($breakpoints, $breakpoint) @return $breakpoint