Skip to content


Sass Basics

This can be extremely powerful when working with brand colors and keeping them consistent throughout the site. Sass is smart and will figure it out for you. You can watch and output to directories by using folder paths as your input and output, and separating them with a colon. You don't have to write all your Sass in a single file. Once Sass is installed, you can compile your Sass to CSS using the sass command.

Think of variables as a way to store information that you want to reuse throughout your stylesheet. Sass uses the $ symbol to make something a variable. You can split it up however you want with the @use rule. Doing math in your CSS is very helpful.

Users of other implementations must use the @import rule instead. In this example: Operations in Sass let us do something like take pixel values and convert them to percentages without much hassle. Go here if you want to learn how to get everything set up. With that in mind, here's an example of some typical styles for a site's navigation: CSS on its own can be fun, but stylesheets are getting larger, more complex, and harder to maintain.

Sass has a handful of standard math operators like + , – , * , math.div() , and % . This is a great way to modularize your CSS and help keep things easier to maintain. You'll need to tell Sass which file to build from, and where to output CSS to. Notice we're using @use 'base'; in the styles.scss file.

The underscore lets Sass know that the file is only a partial file and that it should not be generated into a CSS file. 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. Sass will let you nest your CSS selectors in a way that follows the same visual hierarchy of your HTML.

Sass Basics


p>Before you can use Sass, you need to set it up on your project. Note that the CSS in %equal-heights isn&#39;t generated, because %equal-heights is never extended. 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&#39;t extending a class that&#39;s nested elsewhere in your styles, which can result in unintended selectors in your CSS.

When the Sass is processed, it takes the variables we define for the $font-stack and $primary-color and outputs normal CSS with our variable values placed in the CSS. Sass would watch all files in the app/sass folder for changes, and compile CSS to the public/stylesheets folder. You might name it something like _partial.scss . Be aware that overly nested rules will result in over-qualified CSS that could prove hard to maintain and is generally considered bad practice. If you wanted to watch (instead of manually build) your input.scss file, you&#39;d just add the watch flag to your command, like so: When writing HTML you&#39;ve probably noticed that it has a clear nested and visual hierarchy. Here&#39;s an example: If you want to just browse here, go ahead, but we recommend you go install Sass first.

Sass partials are used with the @use rule. You can even pass in values to make your mixin more flexible. 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. When you use a file you don&#39;t need to include the file extension. Using a file will also include the CSS it generates in your compiled output!

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. Sass has features that don&#39;t exist in CSS yet like nesting, mixins, inheritance, and other nifty goodies that help you write robust, maintainable CSS. A mixin lets you make groups of CSS declarations that you want to reuse throughout your site. Some things in CSS are a bit tedious to write, especially with CSS3 and the many vendor prefixes that exist. For example, running sass input.scss output.css from your terminal would take a single Sass file, input.scss , and compile that file to output.css . This is a great way to organize your CSS and make it more readable.

This is where a preprocessor can help. Only Dart Sass currently supports @use . In our example we&#39;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. Using @extend lets you share a set of CSS properties from one selector to another. In our example we&#39;re going to do some simple math to calculate widths for an article and aside . It helps keep your Sass very DRY.

What the above code does is tells .message , .success , .error , and .warning to behave just like %message-shared . We&#39;ve named our mixin theme . The watch flag tells Sass to watch your source files for changes, and re-compile CSS each time you save your Sass. You can store things like colors, font stacks, or any CSS value you think you&#39;ll want to reuse. This helps you avoid having to write multiple class names on HTML elements.

We&#39;ve created a very simple fluid grid, based on 960px. A partial is a Sass file named with a leading underscore. It is available for use and modification under the MIT License.

You&#39;ll notice that the ul , li , and a selectors are nested inside the nav selector. To create a mixin you use the @mixin directive and give it a name. After you create your mixin, you can then use it as a CSS declaration starting with @include followed by the name of the mixin. The magic happens in the generated CSS , where each of these classes will get the same CSS properties as %message-shared . The most direct way to make this happen is in your terminal.

CSS , on the other hand, doesn&#39;t. That means anywhere that %message-shared shows up, .message , .success , .error , & .warning will too. Here&#39;s an example for theme . You can also watch individual files or directories with the –watch flag.

Sass © 2006–2021 the Sass team, and numerous contributors. We&#39;re also using the variable $theme inside the parentheses so we can pass in a theme of whatever we want. You can create partial Sass files that contain little snippets of CSS that you can include in other Sass files.