How to use CSS variables to make your styles more reusable and maintainable

Pixel Rocket

· 4 min read · 1 year ago

CSS variables, also known as custom properties, are a powerful tool that can make your styles more reusable and maintainable. With CSS variables, you can define a value once and use it multiple times throughout your stylesheet, making it easier to update and manage your styles.

In this article, we will go over how to use CSS variables and how they can help you write more efficient and organized styles.

Defining CSS Variables

To define a CSS variable, you use the -- prefix followed by the variable name and value. You can define a variable anywhere in your stylesheet, but it is typically best to define it in the root element or in a global stylesheet.

:root {
  --main-color: #0066cc;
  --secondary-color: #333333;
}

In this example, we are defining two variables: --main-color and --secondary-color. These variables can now be used throughout the stylesheet to specify colors.

Using CSS Variables

To use a CSS variable, you use the var() function and pass in the variable name as an argument.

body {
  color: var(--main-color);
}

a {
  color: var(--secondary-color);
}

In this example, we are using the --main-color and --secondary-color variables to specify the color of the <body> and <a> elements, respectively.

Overriding CSS Variables

You can override a CSS variable by redefining it in a specific element or descendant element.

:root {
  --main-color: #0066cc;
  --secondary-color: #333333;
}

body {
  color: var(--main-color);
}

a {
  color: var(--secondary-color);
}

.error {
  --secondary-color: #ff0000;
}

.error a {
  color: var(--secondary-color);
}

In this example, we are redefining the --secondary-color variable in the .error class to be red. This will override the value of the --secondary-color variable for any elements with the .error class, including the <a> element.

Pros of Using CSS Variables

There are several benefits to using CSS variables:

They make it easier to update and maintain your styles, as you only need to change the value of a variable in one place.
They make it easier to reuse styles, as you can define a variable once and use it multiple times throughout your stylesheet.
They can improve the organization of your styles, as you can define variables for common values such as colors and sizes.
They can improve the performance of your styles, as they are processed at runtime and can be cached by the browser.

Cons of Using CSS Variables

There are a few drawbacks to using CSS variables:

They are not supported in all browsers, so you may need to use fallbacks or use a polyfill to ensure compatibility.
They can be overridden by more specific styles, which may lead to unexpected results if you are not careful.
They can be more difficult to debug, as they are not always easy to see in the stylesheet or in the browser developer tools.

Tips for Using CSS Variables

Here are a few tips for using CSS variables effectively:

Define variables in the root element or in a global stylesheet to make them available throughout your stylesheet.
Use descriptive and clear names for your variables to make them easy to understand and use.
Use variables for common values such as colors, sizes, and spacing to make it easier to update and maintain your styles.
Be careful when overriding variables, as it can lead to unexpected results if you are not careful.
Use the !default keyword to specify a default value for a variable that can be overridden if needed.

:root {
  --main-color: #0066cc;
  --secondary-color: #333333;
}

.btn {
  --btn-color: #ffffff !default;
  --btn-bg: var(--main-color) !default;
  color: var(--btn-color);
  background-color: var(--btn-bg);
}

.btn-secondary {
  --btn-bg: var(--secondary-color);
}

In this example, we are using the !default keyword to specify default values for the --btn-color and --btn-bg variables. These variables can be overridden if needed, such as in the .btn-secondary class where we are overriding the --btn-bg variable to use the --secondary-color variable.

Conclusion

CSS variables are a powerful tool that can make your styles more reusable and maintainable. By defining and using variables, you can improve the organization and efficiency of your styles and make it easier to update and maintain your website. With a little practice and careful planning, you can start using CSS variables to your advantage in your own projects.

Pixel Rocket Blog