I have a purpose today: to make you better at writing CSS. I want you to take a look at your older projects and think : oh boy, how could I ever write something like this?

Ok, you might think, you have a point. But what about CSS frameworks? That』s what they stand for, isn』t it? That』s how we write good CSS code.

Sure. But there are some downsides:

• It often leads to commonplace design.
• It can be difficult to customize or go beyond CSS frameworks.
• You have to learn them before using them.

And after all, you landed on this article and there』s a reason for that, right? So without further ado, let』s learn how to get better at CSS.

Note: this is not an article about how to design beautiful apps. It』s about learning how to write maintainable CSS code and how to organize it.

SCSS

I』ll be using SCSS in my examples.

SCSS is a CSS pre-processor. Basically, it is a superset of CSS: it adds some cool features like variables, nesting, imports, and mixins.

I』ll talk about what features we are going to use right away.

Variables

You can have variables with SCSS. The main benefit: reusability. Let』s assume that you have a palette of colors for your app. Your primary color is blue.

So you put blue everywhere: the background-color of your button, the color of your title, links. BLUE EVERYWHERE.

And all of a sudden, you don』t like blue. You prefer green.

• Without variables: change all the lines where you put your blue color.
• With variables: just change the variable 😉

// Declare a variable
$primary-color: #0099ff;

// References a variable
h1 {
  color: $primary-color;
}

Nesting

You can also nest your code with SCSS. So this snippet

h1 {
  font-size: 5rem;
  color: blue;
}

h1 span {
  color: green;
}

can become this:

h1 {
  font-size: 5rem;
  color: blue;
  
  span {
    color: green;
  }
}

Much more readable, isn』t it? You spend less time writing complex selectors with nesting.

Partials and imports

When it comes to maintainability and readability, it』s impossible to keep all your code in one big file. It can fit your needs when experimenting or building a small app, but at a professional level…don』t even try. Luckily for us, SCSS allows us to do so.

You can create partial files by naming the file with a leading underscore: _animations.scss , _base.scss , _variables.scss , and so on.

As for importing, well use the @import directive. For example, this is what you can do:

// _animations.scss

@keyframes appear {
  0% {
    opacity: 0;
  }

  100% {
    opacity: 1;
  }
}

// header.scss

@import "animations";

h1 {
  animation: appear 0.5s ease-out;
}

Ah! you might think. You made a mistake here! It』s _animations.scss , not animations 😉

Nope. SCSS is smart enough to know you』re talking about a partial file when you name them that way.

And that』s all we need to know about variables, nesting, partials, and import. SCSS has some more features like mixins, inheritance, and other directives ( @for , @if , …) but I won』t cover them here.

If you want to know more about it, check their docs. They』re well-written and easy to understand.

Organizing CSS Code: The BEM Methodology

I can』t remember how many times I used to give catch-all terms to my CSS classes. You know: .button .page-1 .page-2 .custom-input .

We often don』t know how to name things. And yet it』s important. What if you were building an app and you decided for some reasons to set it aside for some months? Or worse, what if someone takes back the project? If your CSS code hasn』t been properly named, it will be hard to know what you』re talking about at a glance.

BEM helps us solving this problem. BEM is a naming convention and stands for Block Element Modifier.

This methodology can make our code structured, more modular, and reusable. Now let』s explain what is a block, an element, and a modifier.

Blocks

Think of the block as a component. Remember when you played Legos as a kid? Well, let』s go back in time.

How would you build a simple house? You』d need a window, a roof, a door, some walls, and that』s it. Well those are our blocks. They are meaningful on their own.

Naming: the block name : .block
Examples: .card , .form , .post , .user-navigation

Elements

Now how would you build a window with your legos? Well maybe some of them look like frames, and when you assemble four of them, you get a beautiful window. Those are our elements. They are the parts of a block, and they are needed in order to build our block. But out of their block, they are useless.

Naming: block name + __ + element name : .block__element
Examples: .post__author ,.post__date ,.post__text

Modifiers

Now that you』ve built your window, you may want to have a green one or a small one. Those are things called modifiers. They are flags on blocks or elements and they are used to change behaviors, apparences, and so on.

Naming: block name OR element name + -- + modifier name: .block__element--modifier , .block--modifier
Examples: .post--important , .post__btn--disabled

Some notes

• When you』re using BEM, you name with classes and only classes. No IDs, no tags. Just classes.
• Blocks/elements can be nested into other blocks/elements, but they have to be completely independent. Remember that word: independent.
  So don』t put margins on a button because you want it to be placed under a title, otherwise your button will be tied to your title. Use utility classes instead.
• Yes, your HTML file will be overloaded, but don』t worry — it』s a small downside compared to what BEM brings you.

An example

Here is an exercice for you. Go around to your favorite or most used websites and try to think of what would be the blocks, elements, and modifiers.

For example, this is what I imagine on the Google store:

It』s your turn. Be curious and think about what people could have done better. As always, you have to search by yourself, experiment, and create to get better at what you want.

Organizing CSS files: the 7–1 pattern

Still with me? Great! Now let』s see how to organize CSS files. This part will really help you be more productive, and will allow you to instantly find where you have to modify your CSS code.

And to do so, we』ll learn about the 7–1 pattern.

Doesn』t look like anything to me, you might think.

Trust me, it』s fairly simple. You have to follow 2 rules:

1. Write all your partials in 7 different folders.
2. Import them all in one main.scss file located at the root level. And that』s it.

The 7 folders:

• base: in here, put all your boilerplate code. By boilerplate, I mean all CSS code you』re gonna write each time you』ll start a new project. For example: typography rules, animations, utilities (by utilities, I mean classes like margin-right-large , text-center , …) and so on.
• components: The name is explicit here. This folder contains all the components used to build your pages like your buttons, forms, swipers, popups, and so on.
• layout: used to layout the different parts of your page, that is to say, your header, footer, navigation, section, your own grid, and more.
• pages: You may sometimes have a page that has its own specific style, that stands out from what you do usually. Then put your style in the pages folder.
• themes: If you have different themes for your app (dark mode, admin, and so on) put them in this folder.
• abstracts: Put all your functions here, along with variables and mixins. In short, all your helpers.
• vendors: what would be an app or a project without external libraries? Put in the vendors folder all files that don』t depend on you. You may want to add your Font Awesome file, Bootstrap, and stuff like that in here.

The main file

This is where you』ll import all your partials.

@import abstracts/variables;
@import abstracts/functions;

@import base/reset;
@import base/typography;
@import base/utilities;

@import components/button;
@import components/form;
@import components/user-navigation;

@import layout/header;
@import layout/footer;

...

Yes. It seems overwhelming. But I knew you would think that. This architecture is adapted to larger projects, but not to small ones. So here is a version adapted to smaller projects.

sass/
  _animations.scss
  _base.scss
  _buttons.scss
  _header.scss
  ...
  _variables.scss
  main.scss

node-sass <input> <output> [options]

touch index.html
mkdir -p sass/{abstracts,base,components,layout} css
cd sass && touch main.scss

{
  ...
  "scripts": {
    "watch": "node-sass sass/main.scss css/style.css -w",
    "build": "node-sass sass/main.scss css/style.css --output-style compressed"
  },
  ...
}

<!DOCTYPE html>
<html lang=」en」>

<head>
  <meta charset=」UTF-8">
  <meta name=」viewport」 content=」width=device-width, initial-scale=1.0">
  <meta http-equiv=」X-UA-Compatible」 content=」ie=edge」>
  <link rel=」stylesheet」 href=」css/style.css」>
  <title>My app</title>
</head>

<body>
  <h1 class=」heading」>My app</h1>
</body>

</html>

{
  ...
  "scripts": {
    "start": "npm-run-all --parallel liveserver watch",
    "liveserver": "live-server",
    "watch": "node-sass sass/main.scss css/style.css -w",
  },
  ...
}

-webkit-animation-name: myAnimation;
-moz-animation-name: myAnimation; 
-ms-animation-name: myAnimation;

{
  ...
  "scripts": {
    "start": "npm-run-all --parallel liveserver watch",
    "liveserver": "live-server",
    "watch": "node-sass sass/main.scss css/style.css -w",
    "compile": "node-sass sass/main.scss css/style.css",
    "prefix": "postcss css/style.css --use autoprefixer -o css/style.css",
    "compress": "node-sass css/style.css css/style.css --output-style compressed",
    "build": "npm-run-all compile prefix compress"
  ...
}