#hyphenated-lowercase {
  content: '';
}

#snake_case {
  content: '';
}

#camelCase {
  content: '';
}

#PascalCase {
  content: '';

  #Camel_Snake_Case {
    content: '';

    #SCREAMING_SNAKE_CASE {
      content: '';
    }
  }
}

#_with-leading-underscore {
  content: '';
}

#_does_NOT-fitSTANDARD {
  @extend #snake_case;
}

#hyphentated-lowercase {
  color: blue;

  &-with-suffix-extension {
    color: green;

    &-and-another {
      color: red;
    }
  }

  &-INVALID {
    color: pink;
  }
}

#one_parent,
#two_parents,
#third-invalid-parent {
  width: 10px;

  &_valid_child,
  &-invalid-child {
    height: 10px;
  }
}