Learn SASS to create dynamic, reusable styles and efficiently manage and migrate CSS projects.

Web Page Styling—CSS

SASS (Syntactically Awesome Style Sheets) is a scripting language known as a CSS preprocessor. CSS preprocessors are compiled into CSS and, by doing so, extend the default capabilities of CSS. SASS makes authoring stylesheets faster, easier, and more flexible. It’s a welcome helper in the world of web design because anyone who’s created a website knows that CSS is hard. In this module, we’ll learn how to use nesting, variables, mixins, partials, functions, and more to write dynamic and reusable styles of code. We’ll also learn the various methods to structure our projects and bring organization to our stylesheets. By the end of this module, we’ll have advanced knowledge of SASS. We’ll be able to migrate an existing CSS codebase, as well as set up an entire project (and build process) from scratch.

Sass for CSS: Advanced Front-End Development

# Definition
**Control directives** and **expressions** are used in SASS to include styles only under certain defined conditions. 

As a feature, they’re quite advanced and are mainly useful in mixins. Common directives include ```@if```, ```@else```, ```@for``` and ```@while```.

# @if and @else

The ```@if``` and ```@else``` directives are similar to ```if``` and ```else``` statements in JavaScript. 

```@if``` takes an expression and executes the styles contained within its block — if the evaluation **is not false** (or null). 

```@else``` will then be checked, if the previous ```@if``` evaluated to false.

**For example:**



In this lesson, we'll be looking at SASS control directives, which allow us to introduce conditionals and looping into our stylesheets.

Control Directives

Definition

@if and @else