Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.1)
// Compass (v0.13.alpha.10)
// ----

%my-placeholder {
    background:black;
    padding:20px;
    position:relative;
    color:red;
    
    &:before {
        background:purple;
        content:'I was here before you.';
        padding:20px;
        position:absolute;
        top:0;
        right:100%;
    }
    &:after {
        background:pink;
        content:'I come after you.';
        padding:20px;
        position:absolute;
        top:0;
        left:100%;
    }
}

.give-me-more {
    @extend %my-placeholder;
}

SassMeister-output.css

.give-me-more {
  background: black;
  padding: 20px;
  position: relative;
  color: red;
}
.give-me-more:before {
  background: purple;
  content: 'I was here before you.';
  padding: 20px;
  position: absolute;
  top: 0;
  right: 100%;
}
.give-me-more:after {
  background: pink;
  content: 'I come after you.';
  padding: 20px;
  position: absolute;
  top: 0;
  left: 100%;
}