@mixin breakpoint($min: 0, $max : 0) {
@if $min > 0 and $max == 0
{
@media (min-width: $min ) { @content; }
}
@if $min > 0 and $max > 0
{
@media (min-width: $min) and (max-width: $max ) { @content; }
}
@if $max > 0 and $min == 0
{
@media (max-width: $max) { @content; }
}
}