[css] What's the difference between SCSS and Sass?

From what I've been reading, Sass is a language that makes CSS more powerful with variable and math support.

What's the difference with SCSS? Is it supposed to be the same language? Similar? Different?

SASS stands for Syntactically Awesome StyleSheets. It is an extension of CSS that adds power and elegance to the basic language. SASS is newly named as SCSS with some chages, but the old one SASS is also there. Before you use SCSS or SASS please see the below difference.

An example of some SCSS and SASS syntax:

SCSS

$font-stack:    Helvetica, sans-serif;
$primary-color: #333;

body {
  font: 100% $font-stack;
  color: $primary-color;
}

//Mixins
@mixin transform($property) {
  -webkit-transform: $property;
      -ms-transform: $property;
          transform: $property;
}

.box { @include transform(rotate(30deg)); }

SASS

$font-stack:    Helvetica, sans-serif
$primary-color: #333

body
  font: 100% $font-stack
  color: $primary-color

//Mixins
=transform($property)
  -webkit-transform: $property
  -ms-transform:     $property
  transform:         $property

.box
  +transform(rotate(30deg))

Output CSS after Compilation(Same for Both)

body {
  font: 100% Helvetica, sans-serif;
  color: #333;
}
//Mixins
.box {
  -webkit-transform: rotate(30deg);
  -ms-transform: rotate(30deg);
  transform: rotate(30deg);
}

For more guide you can see the official website.

The compact answer:

SCSS refers to the main syntax supported by the Sass CSS pre-processor.

• Files ending with .scss represent the standard syntax supported by Sass. SCSS is a superset of CSS.
• Files ending with .sass represent the "older" syntax supported by Sass originating in the Ruby world.

Original sass is ruby syntax-like, similar to ruby, jade etc...

In those syntaxes, we don't use {}, instead we go with white spaces, also no usage of ;...

In scss syntaxes are more like CSS, but with getting more options like: nesting, declaring, etc, similar to less and other pre-processing CSS ...

They basically do the same thing, but I put couple of lines of each to see the syntax difference, look at the {}, ;, and spaces:

SASS:

$width: 100px
$color: green

div
  width: $width
  background-color: $color

SCSS:

$width: 100px;
$color: green;

div {
  width: $width;
  background-color: $color;
}

I'm one of the developers who helped create Sass.

The difference is UI. Underneath the textual exterior they are identical. This is why sass and scss files can import each other. Actually, Sass has four syntax parsers: scss, sass, CSS, and less. All of these convert a different syntax into an Abstract Syntax Tree which is further processed into CSS output or even onto one of the other formats via the sass-convert tool.

Use the syntax you like the best, both are fully supported and you can change between them later if you change your mind.

From the homepage of the language

Sass has two syntaxes. The new main syntax (as of Sass 3) is known as “SCSS” (for “Sassy CSS”), and is a superset of CSS3’s syntax. This means that every valid CSS3 stylesheet is valid SCSS as well. SCSS files use the extension .scss.

The second, older syntax is known as the indented syntax (or just “Sass”). 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. Although no longer the primary syntax, the indented syntax will continue to be supported. Files in the indented syntax use the extension .sass.

SASS is an interpreted language that spits out CSS. The structure of Sass looks like CSS (remotely), but it seems to me that the description is a bit misleading; it's not a replacement for CSS, or an extension. It's an interpreter which spits out CSS in the end, so Sass still has the limitations of normal CSS, but it masks them with simple code.

The Sass .sass file is visually different from .scss file, e.g.

Example.sass - sass is the older syntax

$color: red

=my-border($color)
  border: 1px solid $color

body
  background: $color
  +my-border(green)

Example.scss - sassy css is the new syntax as of Sass 3

$color: red;

@mixin my-border($color) {
  border: 1px solid $color;
}

body {
  background: $color;
  @include my-border(green);
}

Any valid CSS document can be converted to Sassy CSS (SCSS) simply by changing the extension from .css to .scss.

The basic difference is the syntax. While SASS has a loose syntax with white space and no semicolons, the SCSS resembles more to CSS.

Sass was the first one, and the syntax is a bit different. For example, including a mixin:

Sass: +mixinname()
Scss: @include mixinname()

Sass ignores curly brackets and semicolons and lay on nesting, which I found more useful.

Its syntax is different, and that's the main pro (or con, depending on your perspective).

I'll try not to repeat much of what others said, you can easily google that but instead, I'd like to say a couple of things from my experience using both, sometimes even in the same project.

SASS pro

• cleaner - if you are coming from Python, Ruby (you can even write props with symbol-like syntax) or even the CoffeeScript world, it will come very natural to you - writing mixins, functions and generally any reusable stuff in .sass is much 'easier' and readable than in .scss (subjective).

SASS cons

• whitespace sensitive (subjective), I don't mind it in other languages but here in CSS it just bothers me (issues: copying, tab vs space war, etc).
• no inline rules (this was game breaking for me), you can't do body color: red like you can in .scss body {color: red}
• importing other vendor stuff, copying vanilla CSS snippets - not impossible but very boring after some time. The solution is to either have .scss files (alongside with .sass files) in your project or to convert them to .sass.

Other than this - they do the same job.

Now, what I like to do is to write mixins and variables in .sass and code that will actually compile to CSS in .scss if possible (ie Visual studio doesn't have support for .sass but whenever I work on Rails projects I usually combine two of them, not in one file ofc).

Lately, I'm considering giving Stylus a chance (for a full-time CSS preprocessor) because it allows you to combine two syntaxes in one file (among some other features). That may not be a good direction for a team to take but when you are maintaining it alone - it's ok. The stylus is actually most flexible when syntax is in question.

And finaly mixin for .scss vs .sass syntax comparison:

// SCSS
@mixin cover {
  $color: red;
  @for $i from 1 through 5 {
    &.bg-cover#{$i} { background-color: adjust-hue($color, 15deg * $i) }
  }
}
.wrapper { @include cover }


// SASS
=cover
  $color: red
  @for $i from 1 through 5
    &.bg-cover#{$i}
      background-color: adjust-hue($color, 15deg * $i)
.wrapper
  +cover

SASS is Syntactically Awesome Style Sheets and is an extension of CSS which provides the features of nested rules, inheritance, Mixins whereas SCSS is Sassy Cascaded Style Sheets which is similar to that of CSS and fills the gaps and incompatibilities between CSS and SASS. It was licensed under the MIT license. This article has more about the differences:https://www.educba.com/sass-vs-scss/

Sass (Syntactically Awesome StyleSheets) have two syntaxes:

• a newer: SCSS (Sassy CSS)
• and an older, original: indent syntax, which is the original Sass and is also called Sass.

So they are both part of Sass preprocessor with two different possible syntaxes.

The most important difference between SCSS and original Sass:

SCSS:

• Syntax is similar to CSS (so much that every regular valid CSS3 is also valid SCSS, but the relationship in the other direction obviously does not happen)

• Uses braces {}

• Uses semi-colons ;
• Assignment sign is :
• To create a mixin it uses the @mixin directive
• To use mixin it precedes it with the @include directive
• Files have the .scss extension.

Original Sass:

• Syntax is similar to Ruby
• No braces
• No strict indentation
• No semi-colons
• Assignment sign is = instead of :
• To create a mixin it uses the = sign
• To use mixin it precedes it with the + sign
• Files have the .sass extension.

Some prefer Sass, the original syntax - while others prefer SCSS. Either way, but it is worth noting that Sass’s indented syntax has not been and will never be deprecated.

Conversions with sass-convert:

# Convert Sass to SCSS
$ sass-convert style.sass style.scss

# Convert SCSS to Sass
$ sass-convert style.scss style.sass

The Sass and SCSS documentation

SCSS is the new syntax for Sass. In Extension wise, .sass for the SASS while .scss for the SCSS. Here SCSS has more logical and complex approach for coding than SASS. Therefore, for a newbie to software field the better choice is SCSS.

Difference between SASS and SCSS article explains the difference in details. Don’t be confused by the SASS and SCSS options, although I also was initially, .scss is Sassy CSS and is the next generation of .sass.

If that didn’t make sense you can see the difference in code below.

/* SCSS */
$blue: #3bbfce;
$margin: 16px;

.content-navigation {
  border-color: $blue;
  color: darken($blue, 9%);
}

.border {
  padding: $margin / 2; margin: $margin / 2; border-color: $blue;
}

In the code above we use ; to separate the declarations. I’ve even added all the declarations for .border onto a single line to illustrate this point further. In contrast, the SASS code below must be on different lines with indentation and there is no use of the ;.

/* SASS */
$blue: #3bbfce
$margin: 16px

.content-navigation
  border-color: $blue
  color: darken($blue, 9%)

.border
  padding: $margin / 2
  margin: $margin / 2
  border-color: $blue

You can see from the CSS below that the SCSS style is a lot more similar to regular CSS than the older SASS approach.

/* CSS */
.content-navigation {
  border-color: #3bbfce;
  color: #2b9eab;
}

.border {
  padding: 8px;
  margin: 8px;
  border-color: #3bbfce;
}

I think most of the time these days if someone mentions that they are working with Sass they are referring to authoring in .scss rather than the traditional .sass way.