Generated by SassMeister.com.

SassMeister-input-HTML.html

<button class="btn">Click</button>
<a href="#0" class="btn">Click</a>
<input type="submit" class="btn" value="Click" />

SassMeister-input.scss

// ----
// Sass (v3.4.14)
// Compass (v1.0.3)
// ----

$btn-color: black;
$btn-bg: yellow;
$btn-custom:(
  border-radius: 3px,
  font: bold 12px/1.5 sans-serif,
);

// _components.btn.scss
$btn-color: red !default;
$btn-bg: green !default;
$btn-padding: 1em 2em !default;
$btn-custom:() !default;

.btn {
  display: inline-block;
  text-decoration: none;
  border: none;
  background: none;
  font: inherit;
  cursor: pointer;
  padding: $btn-padding;
  color: $btn-color;
  background-color: $btn-bg;

  @each $property, $value in $btn-custom {
    #{$property}: $value;
  }

}

SassMeister-output.css

.btn {
  display: inline-block;
  text-decoration: none;
  border: none;
  background: none;
  font: inherit;
  cursor: pointer;
  padding: 1em 2em;
  color: black;
  background-color: yellow;
  border-radius: 3px;
  font: bold 12px/1.5 sans-serif;
}

SassMeister-rendered.html

<button class="btn">Click</button>
<a href="#0" class="btn">Click</a>
<input type="submit" class="btn" value="Click" />