.accordion {
  max-width: 600px;

  &__copy {
    display: none;
    padding: 1rem 1.5rem 2rem 1.5rem;

    &--open {
      display: block;
    }
  }
}

.accordion {
  max-width: 600px;
}
.accordion__copy {
  display: none;
  padding: 1rem 1.5rem 2rem 1.5rem;
}
.accordion__copy--open {
  display: block;
}

.alert {
  // The parent selector can be used to add pseudo-classes to the outer
  // selector.
  &:hover {
    font-weight: bold;
  }

  // It can also be used to style the outer selector in a certain context, such
  // as a body set to use a right-to-left language.
  [dir=rtl] & {
    margin-left: 0;
    margin-right: 10px;
  }

  // You can even use it as an argument to pseudo-class selectors.
  :not(&) {
    opacity: 0.8;
  }
}

.alert:hover {
  font-weight: bold;
}
[dir=rtl] .alert {
  margin-left: 0;
  margin-right: 10px;
}
:not(.alert) {
  opacity: 0.8;
}

$spaceamounts: (1, 2, 3, 4, 5);

@each $space in $spaceamounts {
    .m-#{$space} {
        margin: #{$space}rem;
    }
}

$sizes: 40px, 50px, 80px;

@each $size in $sizes {
  .icon-#{$size} {
    font-size: $size;
    height: $size;
    width: $size;
  }
}

git checkout <commit-hash>

git checkout master

Search the working directory for foo():

git grep "foo()"

touch "index.html"

mkdir NAME-OF-YOUR-NEW-DIRECTORY

git remote rename origin upstream

git remote add origin URL_TO_GITHUB_REPO

git push origin master

git checkout -- .