A Short and Irreverently Non-Expert Guide to CSS Preprocessors and Frameworks

It took me a long time to wrap my head around what a CSS preproccessor was and why you might want to use one. I knew everyone was doing it, but for the amount of CSS I was doing, it seemed like overkill. And one more thing to learn! When you are a solo web developer/librarian, it’s always easier to clutch desperately at the things you know well and not try to add more complexity. So this post is for those of you are in my old position. If you’re already an expert, you can skip the post and go straight to the comments to sell us on your own favorite tools.

The idea, by the way, is that you will be able to get one of these up and running today. I promise it’s that easy (assuming you have access to install software on your computer).

Ok, So Why Should I Learn This?

Creating a modern and responsive website requires endless calculations, CSS adjustments, and other considerations that it’s not really possible to do it (especially when you are a solo web developer) without building on work that lots of other people have done. Even if you aren’t doing anything all that sophisticated in your web design, you probably want at minimum to have a nicely proportioned columnar layout with colors and typefaces that are easy to adapt as needed. Bonus points if your site is responsive so it looks good on tablets and phones. All of that takes a lot of math and careful planning to accomplish, and requires much attention to documentation if you want others to be able to maintain the site.

Frameworks and preprocessors take care of many development challenges. They do things like provide responsive columnar layouts that are customizable to your design needs, provide “mixins” of code others have written, allow you to nest elements rather than writing CSS with selectors piled on selectors, and create variables for any elements you might repeat such as typefaces and colors. Once you figure it out, it’s pretty addictive to figure out where you can be more efficient in your CSS. Then if your institution switches the shade of red used for active links, H1s, and footer text, you only have to change one variable to update this rather than trying to find all the places that color appears in your stylesheets.

What You Should Learn

If I’ve convinced you this is something worth putting time into, now you have to figure out where you should spend that time.This post will outline one set of choices, but you don’t need to stick with this if you want to get more involved in learning more.

Sometimes these choices are made for you by whatever language or content management system you are using, and usually one will dictate another. For instance, if you choose a framework that uses Sass, you should probably learn Sass. If the theme you’ve chosen for your content management system already includes preprocessor files, you’ll save yourself lots of time just by going with what that theme has chosen. It’s also important to note that you can use a preprocessor with any project, even just a series of flat HTML files, and in that case definitely use whatever you prefer.

I’m going to point out just a few of each here, since this is basically what I’ve used with which I am familiar. There are lots and lots of all of these things out there, and I would welcome people with specific experience to describe it in the comments.

Before you get too scared about the languages these tools use, it’s really only relevant to beginners insofar as you have to have one of these languages installed on your system to compile your Sass or Less files into CSS.


Sass was developed in 2006. It can be written with Sass or SCSS syntax. Sass runs on Ruby.

Less was developed in 2009. It was originally written in Ruby, but now is in Javascript.

A Completely Non-Comprehensive List of CSS Frameworks

Note! You don’t have to use a framework for every project. If you have a two column layout with a simple breakpoint and don’t need all the overhead, feel free to not use one. But for most projects, frameworks provide things like responsive layouts and useful features (for instance tabs, menus, image galleries, and various CSS tricks) you might want to build in your site without a lot of thought.

  • Compass (runs on Sass)
  • Bootstrap (runs on Less)
  • Foundation (runs on Sass)
  • There are a million other ones out there too. Google search for css frameworks gets “About 4,860,000 results”. So I’m not kidding about needing to figure it out based on the needs of your project and what preprocessor you prefer.
A Quick and Dirty Tutorial for Getting These Up and Running

Let’s try out Sass and Compass. I started working with them when I was theming Omeka, and I run them on my standard issue work Windows PC, so I know you can do it too!


Stir to combine.

Ok it’s not quite that easy. But it’s not a lot harder.

  1. Sass has great installation instructions. I’ve always run it from the command line without a fuss, and I don’t even particularly care for the command line. So feel free to follow those instructions.
  2. If you don’t have Ruby installed already (likely on a standard issue work Windows PC–it is already installed on Macs), install it. Sass suggests RubyInstaller, and I second that suggestion. There are some potential confusing or annoying things about doing it this way, but don’t worry about it until one pops up.
  3. If you are on Windows, open up a new command line window by typing cmd in your start search bar. If you are on a Mac, open up your Terminal app.
  4. Now all you have to do is install Sass with one line of code in your command line client/terminal window: gem install sass. If you are on a Mac, you might get an error message and  have to use the command sudo gem install sass.
  5. Next install Compass. You’ve got it, just type gem install compass.
  6. Read through this tutorial on Getting Started with Sass and Compass. It’s basically what I just said, but will link you out to a bunch of useful tutorials.
  7. If you decide the command line isn’t for you, you might want to look into other options for installing and compiling your files. The Sass installation instructions linked above give a few suggestions.
Working on a Project With These Tools

When you start a project, Compass will create a series of files Sass/SCSS files (you choose which syntax) that you will edit and then compile into CSS files. The easiest way to get started is to head over to the Compass installation page and use their menu to generate the command line text you’ll need to get started.

For this example, I’ll create a new project called acrltest by typing compass create acrltest. In the image below you’ll see what this looks like. This text also provides some information about what to do next, so you may want to copy it to save it for later.


You’ll now have a new directory with several recommended SCSS files, but you are by no means limited to these files. Sass provides the @import command, which imports additional SCSS files, which can either be full CSS files, or “partials”, which allow you to define styles without creating an additional CSS file. Partials start with an underscore. The normal practice is to have a partial _base.scss file, where you identify base styles. You will then import these to your screen.scss file to use whatever you have in that file.

Here’s what this looks like.

On _base.scss, I’ve created two variables.

$headings: #345fff;
$links: #c5ff34;

Now on my screen.scss file, I’ve imported my file and can use these variables.

@import "base";

a {
    color: $links;

 h1 {
    color: $headings;

Now this doesn’t do anything yet since there are no CSS files that you can use on the web. Here’s how you actually make the CSS files.

Open up your command prompt or terminal window and change to the directory your Compass project is in. Then type compass watch, and Compass will compile your SCSS files to CSS. Everytime you save your work, the CSS will be updated, which is very handy.


Now you’ll have something like this in the screen.css file in the stylesheets directory:


/* line 9, ../sass/screen.scss */
a {
  color: #c5ff34;

/* line 13, ../sass/screen.scss */
h1 {
  color: #345fff;

Note that you will have comments inserted telling you where this all came from.

Next Steps

This was an extremely basic overview, and there’s a lot more I didn’t cover–one of the major things being all the possibilities that frameworks provide. But I hope you start to get why this can ultimately make your life easier.

If you have a little experience with this stuff, please share it in the comments.

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