The Power of CSS Custom Properties

Published on July 25, 2020

Introduction

CSS Custom Properties (also known as CSS Variables) are a powerful feature in CSS that allows you to define and use values in your stylesheets. In this post, we will explore the benefits of using CSS Custom Properties and how they can be used to create themeable design systems.

What is CSS Custom Properties?

CSS Custom Properties are variables that you can define in your stylesheet and then reference throughout your code. These variables can hold any value, including colors, fonts, and even entire CSS rulesets. One of the main benefits of using CSS Custom Properties is that they make it easy to manage and reuse values across multiple components.

How do CSS Custom Properties Work?

To use CSS Custom Properties in your stylesheets, you first need to define them at the top level of your code. For example:

:root {
  --primary-color: #3498db;
}

Once you have defined a Custom Property, you can reference it throughout your code using the var() function. For example:

body {
  background-color: var(--primary-color);
}

You can also use CSS Custom Properties to create themeable design systems. By defining a set of Custom Properties at the top level of your code, you can easily switch between different themes by changing the values of those properties. For example:

:root {
  --primary-color: #3498db;
  --secondary-color: #f57c00;
}

body {
  background-color: var(--primary-color);
  color: var(--secondary-color);
}

In this example, we have defined two Custom Properties at the top level of our code: --primary-color and --secondary-color. We can then reference these properties throughout our code to set the background color and text color of our body element. By changing the values of these properties, we can easily switch between different themes.

Best Practices for Using CSS Custom Properties

Using CSS Custom Properties is a powerful tool, but it’s important to use them correctly to avoid any issues with your code. Here are some best practices to keep in mind:

• Use descriptive names for your Custom Properties. This will make it easier to understand what each property does and how it should be used.
• Keep your Custom Properties organized by grouping them together at the top level of your code. This will make it easier to find and reference specific properties throughout your code.
• Avoid using Custom Properties as global variables. While it is possible to define Custom Properties at the top level of your code, it’s generally better to avoid doing so and instead use them locally where needed. This will help keep your code organized and make it easier to maintain.
• Use Custom Properties sparingly. While they can be very useful for managing values across multiple components, using too many Custom Properties can make your code harder to read and maintain. Try to use them only when necessary and avoid overusing them.

Conclusion

CSS Custom Properties are a powerful feature in CSS that allows you to define and use values in your stylesheets. By using these variables, you can create themeable design systems and easily manage values across multiple components. By following best practices for using CSS Custom Properties, you can write more organized and maintainable code.