Check out example codes for "css vs scss". It will help you in understanding the concepts better.

Code Example 1

/* Answer to: css vs scss */

  Sass has two syntaxes. The most commonly used syntax is known as “SCSS”
  (for “Sassy CSS”), and is a superset of CSS3's syntax. ... Inspired by
  Haml's terseness, it's intended for people who prefer conciseness over
  similarity to CSS. Instead of brackets and semicolons, it uses the
  indentation of lines to specify blocks.

  Check the full answer by clicking on the source but the main thing here is:
  SCSS is a **SUPERSET** of the CSS3's syntax.

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