Rather than repeating the same selectors over and over again, you can write one style rules inside another. Sass will automatically combine the outer rule's selector with the inner rule's.
Sass Nested Rules is a backbone of sass.
The following example will demonstrate how to apply Sass nested rules.
The deeper you nest, the more bandwidth it takes to serve your CSS and the more work it takes the browser to render it. So, it is recommended to keep those selectors shallow whenever possible.