Generated by SassMeister.com.

SassMeister-input-HTML.html

<a href="#0" class="c-btn">
  <span class="c-btn__text">Close</span>
</a>

<hr />

<a href="#0" class="c-btn  is-icon">
  <span class="c-btn__icon">X</span>
  <span class="c-btn__text">Close</span>
</a>

<hr />

<a href="#0" class="c-btn">
  <span class="c-btn__icon">X</span>
  <span class="c-btn__text">Close</span>
</a>

SassMeister-input.scss

// ----
// Sass (v3.4.20)
// Compass (v1.0.3)
// ----

@mixin hide($style: 'physically') {
  @if ($style == 'physically') {
    display: none;
  } @elseif ($style == 'visually') {
    visibility: hidden;
  } @elseif ($style == 'accessibly') {
    position: absolute !important;
    width: 1px; 
    height: 1px;
    overflow: hidden;
    clip: rect(1px, 1px, 1px, 1px);
  }
}

.c-btn {

  &.is-icon .c-btn__text {
    @include hide('accessibly');
  }

}

SassMeister-output.css

.c-btn.is-icon .c-btn__text {
  position: absolute !important;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(1px, 1px, 1px, 1px);
}

SassMeister-rendered.html

<a href="#0" class="c-btn">
  <span class="c-btn__text">Close</span>
</a>

<hr />

<a href="#0" class="c-btn  is-icon">
  <span class="c-btn__icon">X</span>
  <span class="c-btn__text">Close</span>
</a>

<hr />

<a href="#0" class="c-btn">
  <span class="c-btn__icon">X</span>
  <span class="c-btn__text">Close</span>
</a>