What is SMACSS?

Smacss (Scalable and Modular Architecture for CSS) is a style guide that follows five simple categories. SMACSS is a way to examine your design process and to fit those rigid frameworks into a flexible thought process. It is an attempt to document a consistent approach to site development when using CSS. And really, who isn’t building a site with CSS these days?!

Which are these categories?

The idea of this architecture is to not mix code of several categories on a single file because it can be very complicated to find a simple line of code to change. Most of the purpose of this categorization is to codify patterns —things that repeat themselves within our design. Repetition results in less code, easier maintenance, and greater consistency in the user experience.

Base: are the defaults values. They are like the padding, margin, border, font and other properties, this values are used on the entire web site and all elements.

Layout: divides a page into sections with elements like header, footer, main page, etc. Layouts hold one or more modules together. Often developers show layout elements by prefixing the class with l-, e.g. l-header, l-footer.

Modules: are the reusable, modular parts of our design like navbar, sidebar and some elements that are repeated in the site.

State: are ways to describe how our modules or layouts will look when they are into a particular state (e.g. active, inactive, expanded, hidden). These are prefixed with is-, e.g. is-active, is-inactive, is-expanded, is-hidden.

Theme: Theme rules are similar to state rules in that they describe how modules or layouts might look. It is more applicable for larger sites with shared elements that look different throughout.

Following these simple rules you can order your files easily. At the time you need to find a line or a file, it will be more easy because you know where it is and you not will lose too much time. Also, working with a team will be more easy to understood the CSS and they will not have issues with the code; remembers that your code have be scalable and easy to understand.