CSS if() brings conditional styling to the web

In the ever-evolving landscape of web development, the introduction of the CSS if() function marks a significant advancement in how developers can apply conditional styling directly within stylesheets. This feature, first introduced in Chrome 137 in May 2025, allows for more dynamic and responsive designs without the need for external JavaScript or complex CSS workarounds. By enabling inline conditional logic, the if() function streamlines the development process and enhances the maintainability of codebases.

The if() function operates by evaluating specified conditions and applying corresponding styles based on the outcome. Its syntax is straightforward, resembling traditional conditional statements found in programming languages. This approach not only simplifies the code but also improves readability and reduces the potential for errors. As of October 2025, the if() function is supported in Chrome 137+, Edge 137+, and Android browsers, with ongoing efforts to expand its compatibility across other platforms.

Understanding the Syntax of the if() Function

The if() function follows a clear and concise syntax that mirrors traditional conditional statements. It evaluates a condition and applies a specified value if the condition is true; otherwise, it applies an alternative value. This structure allows developers to write more intuitive and maintainable CSS code. For example, to set the background color based on a custom property, one might use:

background-color: if(
  style(--theme: dark): #333;
  else: #fff
);

In this example, if the custom property --theme is set to ‘dark’, the background color will be ‘#333’; otherwise, it will default to ‘#fff’. This conditional logic is evaluated inline, eliminating the need for separate media queries or JavaScript functions to achieve similar effects.

Types of Conditions Supported by if()

The if() function supports three primary types of conditions, each catering to different scenarios in web development:

• Style Queries (style()): These conditions check the value of custom properties (CSS variables) to apply styles accordingly. This is particularly useful for theming and dynamic styling based on user preferences or application state.
• Media Queries (media()): These conditions evaluate media features, such as viewport width or device orientation, allowing for responsive design adjustments directly within the CSS.
• Feature Queries (supports()): These conditions test whether the browser supports specific CSS features, enabling the application of styles that rely on newer or experimental properties without affecting unsupported browsers.

By incorporating these conditions, the if() function provides a versatile tool for developers to create adaptive and feature-rich web designs.

Practical Applications of the if() Function

The introduction of the if() function opens up numerous possibilities for developers to implement conditional styling directly within their stylesheets. One practical application is in theming, where the background color can be set based on a custom property:

background-color: if(
  style(--theme: dark): #333;
  else: #fff
);

Another use case is in responsive design, where styles can be adjusted based on media features:

font-size: if(
  media(width: 600px): 14px;
  else: 16px
);

Additionally, feature queries can be utilized to apply styles based on browser support for specific CSS properties:

border: 2px solid if(
  supports(color: lch(70% 60 30)): lch(70% 60 30);
  else: #888
);

These examples demonstrate how the if() function can simplify the application of conditional styles, leading to cleaner and more efficient CSS code.

Browser Support and Compatibility Considerations

As of October 2025, the if() function is supported in Chrome 137+, Edge 137+, and Android browsers. However, support in other browsers, such as Firefox and Safari, is limited or nonexistent. Developers should be aware of these compatibility constraints and consider implementing fallback strategies to ensure a consistent user experience across different platforms. Utilizing feature queries and providing alternative styles can help mitigate issues arising from unsupported browsers.

Best Practices for Implementing the if() Function

To effectively incorporate the if() function into your CSS, consider the following best practices:

• Use Descriptive Custom Properties: When utilizing style() conditions, ensure that custom properties have clear and descriptive names to enhance code readability and maintainability.
• Provide Fallbacks for Unsupported Browsers: Implement fallback styles using feature queries or separate stylesheets to accommodate browsers that do not support the if() function.
• Test Across Multiple Browsers: Regularly test your website or application across different browsers and devices to identify and address any compatibility issues related to the if() function.

By adhering to these practices, developers can leverage the full potential of the if() function while maintaining a robust and user-friendly web experience.

Future Prospects and Evolution of Conditional Styling in CSS

The introduction of the if() function represents a significant step forward in the evolution of CSS, bringing conditional logic directly into stylesheets. This development aligns with ongoing efforts to enhance the capabilities of CSS and reduce reliance on external scripting languages for dynamic styling. As browser support for the if() function expands, it is anticipated that this feature will become a standard tool in the web developer’s toolkit, enabling more sophisticated and responsive web designs.

Looking a, the CSS Working Group continues to refine and expand the CSS Conditional Rules Module, with the goal of providing developers with more powerful and flexible tools for styling web content. The if() function is expected to evolve, with potential enhancements such as support for additional condition types and improved interoperability across different browsers and platforms. Staying informed about these developments will be crucial for developers aiming to leverage the latest advancements in CSS for their projects.

In conclusion, the CSS if() function introduces a powerful mechanism for applying conditional styling directly within stylesheets, streamlining the development process and enhancing the responsiveness of web designs. By understanding its syntax, applications, and best practices, developers can effectively incorporate this feature into their projects, paving the way for more dynamic and adaptable web experiences.

As the web development landscape continues to evolve, embracing new features like the if() function will be essential for creating modern, efficient, and user-friendly web applications. By staying abreast of these advancements and integrating them thoughtfully into development workflows, developers can ensure that their projects remain at the forefront of web design innovation.