Sass Mixins

$default-padding: 10px;
@mixin pad($n: $default-padding) {
    padding: $n;
}
body {
    @include pad(15px);
}

@mixin pad($n: 10px) {
    padding: $n;
}

body {
    @include pad(15px);
}

@mixin font-size($n) {
    font-size: $n * 1.2em;
}

body {
    @include font-size(2);
}