Sass referencing parent selectors using the ampersand character within nested selectors

Question

Just when I thought Sass was the coolest thing since sliced bread, it had to go and let me down. I'm trying to use the ampersand to select a parent of a nested item. It's a complex selection and its returning some unexpected results...

My sass:

.page--about-us {
  a {
    text-decoration:none;
  }
  .fa-stack {
    .fa {
      color:pink;
    }
    a & {
      &:hover {
        .fa-circle-thin {
          color:red;
        }
        .fa-twitter {
          color:blue;
        }
      }
    }
  }
}

Outputted CSS:

.page--about-us a {
  text-decoration: none;
}
.page--about-us .fa-stack .fa {
  color: pink;
}
a .page--about-us .fa-stack:hover .fa-circle-thin {
  color: red;
}
a .page--about-us .fa-stack:hover .fa-twitter {
  color: blue;
}

Expected Output (Note the placement of the a tag):

.page--about-us a {
  text-decoration: none;
}
.page--about-us .fa-stack .fa {
  color: pink;
}
.page--about-us a .fa-stack:hover .fa-circle-thin {
  color: red;
}
.page--about-us a .fa-stack:hover .fa-twitter {
  color: blue;
}

Demo: http://sassmeister.com/gist/8ed68bbe811bc9526f15

Answer 1

You can store the parent selector in a variable!

Take the following BEM-like SASS:

.content-block {
    &__heading {
        font-size: 2em;
    }

    &__body {
        font-size: 1em;
    }

    &--featured {
        &__heading {
            font-size: 4em;
            font-weight: bold;
        }
    }
}

The selector inside of .content-block--featured is going to be .content-block--featured .content-block--featured__heading which might not be what you're after.

It's not as elegant as the single ampersand but you can stash the parent selector into a variable! So to get what you might be after from the above example without hard-coding the parent selector:

.content-block {
    $p: &; // store parent selector for nested use

    &__heading {
        font-size: 2em;
    }

    &__body {
        font-size: 1em;
    }

    &--featured {
        #{$p}__heading {
            font-size: 4em;
            font-weight: bold;
        }
    }
}

---

So, OP, in your case you might try something like this:

.page--about-us {
    $about: &; // store about us selector

    a {
        text-decoration:none;
    }

    .fa-stack {
        .fa {
            color:pink;
        }

        #{$about} a & {
            &:hover {
                .fa-circle-thin {
                    color:red;
                }
                .fa-twitter {
                    color:blue;
                }
            }
        }
    }
}

Answer 2

This is the normal behavior, as described in Sass documentation (link):

& will be replaced with the parent selector as it appears in the CSS. This means that if you have a deeply nested rule, the parent selector will be fully resolved before the & is replaced.

Meaning:

.foo {
  .bar {
    .baz & {
      color: red;
    }
  }
}

Will render as:

.baz .foo .bar {
  color: red;
}

And not:

.baz .bar {
  color: red;
}

---

The right way to get your expected result is this one:

.page--about-us {
  a {
    text-decoration:none;

    .fa-stack:hover {
      .fa-circle-thin {
        color:red;
      }
      .fa-twitter {
        color:blue;
      }
    }
  }
  .fa-stack {
    .fa {
      color:pink;
    }
  }
}