Check out example codes for "Mergeable selector SCSS-lint Solved". It will help you in understanding the concepts better.

Code Example 1

.arrow--right {
  border-bottom: 12px solid transparent;
  border-left: 12px solid $border-color;
  border-top: 12px solid transparent;
  cursor: pointer;
  height: 0;
  transform: rotate(0deg);
  transition: transform .1s linear;
  width: 0;

  &:hover {
    border-left-color: $brand-highlight;
  }
}

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