CSS :root Selector

Posted in CSS Tutorial

Updated on Sep 18, 2024

By Mari Selvan

👁️ 4 - Views

⏳ 4 mins

💬 0

Photo Credit to CodeToFun

🙋 Introduction

The :root selector in CSS represents the highest-level parent element in the document tree, which is usually the <html> element in an HTML document.

It is especially useful when defining global CSS variables (also known as CSS custom properties) and when applying global styles that affect the entire webpage.

💡 Syntax

The signature of the :root Selector is as follows:

Syntax

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:root {
    /* CSS properties */
}

The :root selector targets the root element of the document, and it behaves similarly to the html selector, but with a higher specificity, making it more suitable for certain use cases like custom properties.

📝 Example

Here’s an example demonstrating the use of the :root selector to define CSS variables that are applied globally across the page.

☠️ HTML

HTML

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS :root Selector Example</title>
    <link rel="stylesheet" href="styles.css">
</head>
<body>
    <h1>Hello World</h1>
    <p>This is a simple example demonstrating the power of the :root selector in CSS.</p>
</body>
</html>

🎨 CSS

CSS

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:root {
    --primary-color: #3498db;
    --secondary-color: #2ecc71;
    --font-size: 16px;
}

body {
    font-size: var(--font-size);
    color: var(--primary-color);
}

h1 {
    color: var(--secondary-color);
}

In this example:

CSS variables are declared within the :root selector to store values for primary color, secondary color, and font size.
These variables are then used throughout the CSS file with the var() function to apply consistent styles across the webpage.

💬 Usage Tips

The :root selector is often used when defining custom properties (CSS variables) to ensure they are available globally across the entire document.
Because :root has higher specificity than the html selector, it can be a good option when you need to override styles more precisely.
You can combine :root with media queries to create responsive variables for dynamic designs.

📝 Example: Responsive Design with :root

CSS

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:root {
    --font-size: 16px;
}

@media (min-width: 768px) {
    :root {
        --font-size: 18px;
    }
}

body {
    font-size: var(--font-size);
}

In this case, the :root selector adjusts the global font size based on the screen width, providing a more responsive user experience.

⚠️ Common Pitfalls

Avoid overusing the :root selector to define all styles, as it is mainly intended for global settings, like variables. It’s best to use it for properties that need to be accessible across the entire document.
Be mindful of browser support for CSS variables. While most modern browsers fully support them, some older versions might not render styles using var() correctly.

🎉 Conclusion

The CSS :root selector is a powerful tool for defining and managing global styles, particularly when working with CSS variables. Its higher specificity makes it a great choice for applying global values, ensuring consistency across your web pages.

By using :root efficiently, you can simplify your CSS and make it more maintainable and scalable.