Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="container">
<section class="first-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>

<section class="second-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>

<section class="third-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>

<section class="fourth-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>
</div>

SassMeister-input.scss

// ----
// Sass (v3.4.12)
// Compass (v1.0.3)
// ----

.extend-me {
  color: blue;
}

.class {
  @extend .extend-me;
  background: black;
}

.extend-me {
  font-size: 16px;
}

SassMeister-output.css

.extend-me, .class {
  color: blue;
}

.class {
  background: black;
}

.extend-me, .class {
  font-size: 16px;
}

SassMeister-rendered.html

<div class="container">
<section class="first-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>

<section class="second-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>

<section class="third-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>

<section class="fourth-section">
    <img src="http://placekitten.com/g/200/200" >
    <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit</p>
</section>
</div>