Before you can use Sass, you need to set it up on your project. If you want to just browse here, go ahead, but we recommend you go install Sass first. Go here if you want to learn how to get everything setup.
CSS on its own can be fun, but stylesheets are getting larger, more complex, and harder to maintain. This is where a preprocessor can help. Sass lets you use features that don't exist in CSS yet like variables, nesting, mixins, inheritance and other nifty goodies that make writing CSS fun again.
Once you start tinkering with Sass, it will take your preprocessed Sass file and save it as a normal CSS file that you can use in your website.
The most direct way to make this happen is in your terminal. Once Sass is installed, you can compile
your Sass to CSS using the
sass command. You'll need to tell Sass
which file to build from, and where to output CSS to. For example, running
sass input.scss output.css from your terminal would take a single Sass file,
input.scss, and compile that file to
You can also watch individual files or directories with the
--watch flag. The watch flag
tells Sass to watch your source files for changes, and re-compile CSS each time
you save your Sass. If you wanted to watch (instead of manually build) your
you'd just add the watch flag to your command, like so:
sass --watch input.scss output.css
You can watch and output to directories by using folder paths as your input and output, and separating them with a colon. In this example:
sass --watch app/sass:public/stylesheets
Sass would watch all files in the
app/sass folder for changes, and compile CSS to the
Think of variables as a way to store information that you want to reuse throughout your stylesheet. You
can store things like colors, font stacks, or any CSS value you think you'll
want to reuse. Sass uses the
$ symbol to make something a variable. Here's an example:
When the Sass is processed, it takes the variables we define for the
$primary-color and outputs normal CSS with our variable values
placed in the CSS. This can be extremely powerful when working with brand
colors and keeping them consistent throughout the site.
When writing HTML you've probably noticed that it has a clear nested and visual hierarchy. CSS, on the other hand, doesn't.
Sass will let you nest your CSS selectors in a way that follows the same visual hierarchy of your HTML. Be aware that overly nested rules will result in over-qualified CSS that could prove hard to maintain and is generally considered bad practice.
With that in mind, here's an example of some typical styles for a site's navigation:
You'll notice that the
a selectors are nested
nav selector. This is a great way to organize your CSS
and make it more readable.
You can create partial Sass files that contain little snippets of CSS that you
can include in other Sass files. This is a great way to modularize your CSS and
help keep things easier to maintain. A partial is a Sass file named with a leading underscore. You might
name it something like
_partial.scss. The underscore lets Sass know that the file
is only a partial file and that it should not be generated into a CSS
file. Sass partials are used with the
Only Dart Sass currently supports @use. Users of other implementations must use the
@import rule rule instead.
You don't have to write all your Sass in a single file. You can split it up however you want with the
@use rule. This rule loads another Sass file as a module, which means you can refer
to its variables, mixins, and functions in your Sass file with a namespace based on
the filename. Using a file will also include the CSS it generates in your
Notice we're using
@use 'base'; in the
styles.scss file. When you use a file
you don't need to include the file extension. Sass is smart and will figure it out for you.
Some things in CSS are a bit tedious to write, especially with CSS3 and the many vendor prefixes that exist. A mixin lets you make groups
of CSS declarations that you want to reuse throughout your site. You
can even pass in values to make your mixin more flexible. A good use of a mixin is for vendor
prefixes. Here's an example for
To create a mixin you use the
@mixin directive and give it a name. We've named our mixin
transform. We're also using the variable
$property inside the parentheses so we
can pass in a transform of whatever we want. After you create your mixin, you can then use it as a CSS declaration starting with
@include followed by the name of
This is one of the most useful features of Sass. Using
@extend lets you share a set of
CSS properties from one selector to another. It helps keep your Sass very DRY. In our example we're going to create a simple series of messaging for errors,
warnings and successes using another feature which goes hand in hand with extend, placeholder classes.
A placeholder class is a special type of class that only prints when it is extended, and can help
keep your compiled CSS neat and clean.
What the above code does is tells
.warning to behave just like
%message-shared. That means anywhere that
%message-shared shows up,
.warning will too. The magic happens in the generated CSS, where each of these classes will get the same CSS
%message-shared. This helps you avoid having to write multiple class names on
You can extend most simple CSS selectors in addition to placeholder classes in Sass, but using placeholders is the easiest way to make sure you aren't extending a class that's nested elsewhere in your styles, which can result in unintended selectors in your CSS.
Note that the CSS in
%equal-heights isn't generated, because
%equal-heights is never extended.
Doing math in your CSS is very helpful. Sass has a handful of standard math
%. In our
example we're going to do some simple math to calculate widths for an
We've created a very simple fluid grid, based on 960px. Operations in Sass let us do something like take pixel values and convert them to percentages without much hassle.