Generated by SassMeister.com.

SassMeister-input-HTML.html

<a href="#nogo" class="button--PRIMARY">Primary Button</a>
<br />
<a href="#nogo" class="button--SECONDARY">Secondary button</a>

SassMeister-input.scss

// ----
// libsass (v3.2.5)
// ----

@mixin button($background, $margin: null, $padding: null){
  display: inline-block;
  color: #fff;
  text-decoration: none;
  background-color: $background;
  
  margin: $margin;
  padding: $padding;
}

.button {
  padding: 1em;
  
  &--PRIMARY {
    @include button(green, 1em, 1em);
  }
  
  &--SECONDARY {
    @include button(pink, 1em, 1em);
  }
}

SassMeister-output.css

.button {
  padding: 1em;
}

.button--PRIMARY {
  display: inline-block;
  color: #fff;
  text-decoration: none;
  background-color: green;
  margin: 1em;
  padding: 1em;
}

.button--SECONDARY {
  display: inline-block;
  color: #fff;
  text-decoration: none;
  background-color: pink;
  margin: 1em;
  padding: 1em;
}

SassMeister-rendered.html

<a href="#nogo" class="button--PRIMARY">Primary Button</a>
<br />
<a href="#nogo" class="button--SECONDARY">Secondary button</a>