CSS has evolved significantly over the years, and one of its most powerful enhancements is the introduction of CSS Custom Properties, also known as CSS Variables. Integrating these with Sass can elevate your styling game. This article will guide you through the process of using CSS Custom Properties with Sass effectively.

Installation

To get started with CSS Custom Properties in your Sass project, you need to install the css-vars. You can do this through various methods:

• With npm: npm install css-vars
• With yarn: yarn add css-vars
• Manually: Get the main mixin file [this file]

Once you have the file, you can include it in your project using an @import statement:

scss
@import [%PATH%]css-vars/css-vars;

Usage

To declare CSS variables, you will use the @include css-vars(map of variables) function. Here’s where the magic of Sass variables comes into play!

scss
$css-vars-use-native: true;
$white-color: #fff;
$base-font-size: 10px;

@include css-vars((
    --main-color: #000,
    --main-bg: $white-color,
    --main-font-size: 1.5 * $base-font-size,
    --padding-top: calc(2vh + 20px)
));

After declaring your variables, you can use them in your stylesheets with the var() function:

scss
body {
    color: var(--main-color);
    background: var(--main-bg, #f00);
    font-size: var(--main-font-size);
    padding: var(--padding-top) 0 10px;
}

An Analogy for Better Understanding

Think of CSS Custom Properties as a recipe card in a kitchen. When you create a dish, you can refer back to that recipe card whenever you need to know the ingredients and their quantities. Similarly, CSS variables allow you to refer back to certain values throughout your styles. Now, when you mix that with Sass, you are gifting your recipe card with some fancy electronic features, allowing you to adjust all similar dishes with just a single tweak on your card without having to rewrite your entire recipe!

CSS Output

The output from the above CSS would look like this:

css
body {
    color: #000;
    background: #fff;
    font-size: 15px;
    padding: calc(2vh + 20px) 0 10px;
}

Declaration in Selectors and Reassigning Variables

You can declare variables in the global scope or inside specific selectors. For example:

scss
@include css-vars((
    --line-height: 1,
    --main-font-family: (Helvetica, Arial, sans-serif)
));

header {
    @include css-vars((
        --header-padding: 10px 20px,
        --line-height: 1.428571429,
        --border-color: rebeccapurple
    ));
    padding: var(--header-padding);
    line-height: var(--line-height);
}

Default Values

The var() function allows you to set default values for undefined variables:

scss
::after {
    content: var(--external-link, external link);
}

Advantages of the Mixin

Using this mixin provides helpful debug information such as:

• Logs when a variable was not assigned but used.
• Logs when a variable is reassigned.
• Information on default values being used if a variable is not defined.

To enable debug messages, simply set:

scss
$css-vars-debug-log: true;

Troubleshooting

Here are a few tips in case you encounter issues:

• If your variables aren’t applying as expected, ensure you have set the $css-vars-use-native flag appropriately.
• Check your browser support for CSS Custom Properties by visiting Can I Use.
• Enable debug logging to pinpoint variable issues in Sass compilation.

For more insights, updates, or to collaborate on AI development projects, stay connected with fxis.ai.

Conclusion

By mastering the usage of CSS Custom Properties with Sass, you can streamline your styling process and enhance the maintainability of your styles. At fxis.ai, we believe that such advancements are crucial for the future of AI, as they enable more comprehensive and effective solutions. Our team is continually exploring new methodologies to push the envelope in artificial intelligence, ensuring that our clients benefit from the latest technological innovations.