Combining selector sequences into @extend in SASS

If we need to combine selector sequences, we also use the @extend directive:

Let's consider the following example:

style.scss#main .list p {
  font-weight: bold;
}
#sub .resume .link {
  @extend p;
}

Note in the compiled code in the css file that when combining two sequences that do not have common selectors, new selectors are automatically generated: one with the first sequence before the second, and one with the second sequence before the first:

style.css#main .list p,
#main .list #sub .resume .link, #sub .resume #main .list .link {
  font-weight: bold;
}

In case the sequences have a common selector, they will be merged together and only the differences (if any) will be alternated. In the following example, both sequences have the identifier #main:

style.scss#main .list p {
  font-weight: semi-bold;
}
#main .resume .link {
  @extend p;
}

As a result of compilation, these two identifiers will be combined:

style.css#main .list p,
#main .list #sub .resume .link, #sub .resume #main .list .link {
  font-weight: bold;
}

styles.scssdiv p {
  font-size: 12px;
  padding-bottom: 4px;
}
link button #card-title {
  @extend p;
}