Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.14)
// Compass (v1.0.1)
// ----

// Using Sass' ability to nest selectors, tidy up this code.

.main-nav {
  background-color: white;
  left: 0;
  position: fixed;
  top: 0;
  width: 100%;

  &__list {
    padding-left: 3.14%;
    li {
      border-left: 1px solid red;
      display: block;
      float: left;
      padding: 4px 1em;
    }

    &__list a {
      color: red;
      font-size: 1.4em;
      text-align: center;
    }
  }
}

SassMeister-output.css

.main-nav {
  background-color: white;
  left: 0;
  position: fixed;
  top: 0;
  width: 100%;
}
.main-nav__list {
  padding-left: 3.14%;
}
.main-nav__list li {
  border-left: 1px solid red;
  display: block;
  float: left;
  padding: 4px 1em;
}
.main-nav__list__list a {
  color: red;
  font-size: 1.4em;
  text-align: center;
}