CSS Gets Smarter: Inline Conditional Logic with the New if() Function

CSS that responds to conditions on the fly without relying on JavaScript or convoluted workarounds has always been a dream of web developers. The new if() function, introduced in the CSS 2025 snapshot, finally brings conditional style application natively to CSS. 

It marks a significant leap forward, allowing developers to embed conditional logic directly into their stylesheets and transforming how responsive and adaptive design is handled.

Understanding the if() Function

At its core, the if() function brings programming-like conditional statements into CSS. Designers and developers can now declare property values based on real-time conditions, all within a single rule. This streamlines stylesheets and eliminates the need for extra code blocks or JavaScript for dynamic styling.

• Syntax: The if() function uses semi-colon-separated condition-value pairs, echoing conditional constructs found in languages like JavaScript.
  
  
• Condition Sources: It leverages media queries, feature queries, and style queries as its decision-making mechanisms.
  
  
• Else Support: Developers can provide a default fallback value, ensuring graceful degradation with an else-like clause.
  
  
• Broad Integration: The function can be used across any property, selector, or class, offering flexibility and reusability.

Developer Benefits: New Possibilities Unlocked

The if() function doesn't just improve code; it fundamentally changes what developers can achieve with CSS. Here’s how:

• Create inline media queries for adapting to user preferences, such as switching between light and dark modes.
  
  
• Use support queries to detect browser or hardware features and adjust styles accordingly.
  
  
• Reflect dynamic UI states by swapping visuals or layouts based on application status or user actions, all from within CSS.

Industry experts like Google’s Una Kravets highlight that this brings a new dimension of responsiveness, all without leaving the styling layer.

//Example of if conditional usage in CSS
div {
  background-image: if(
    style(--scheme: primary): linear-gradient(#caf0f8, white, #caf0f8);
    style(--scheme: secondary): linear-gradient(#ffc971, white, #ffc971);
    else: none;
  );
}

Current Browser Support

While the if() function is groundbreaking, support is still rolling out. As of October 2025, it is available in Chrome and Edge on desktop, and Chrome for Android and the Android browser on mobile. However, Safari, Firefox, and most other mobile browsers have yet to implement it. Developers should monitor compatibility and plan fallbacks when deploying in production environments.

• Desktop: Supported in Chrome and Edge; unsupported in Safari and Firefox.
• Mobile: Available only in Chrome for Android and the Android browser.

As demand grows, industry watchers expect adoption to spread across major browsers.

How if() Works: Practical Usage

To leverage if(), start by defining custom properties (CSS variables) that can be set dynamically. Inside a CSS rule, use the if() function to decide which value should apply based on current conditions. This enables everything from swapping images based on site themes to changing layouts for device capabilities—with no extra JavaScript required.

CSS Matures: A New Programming Paradigm

The arrival of if() signals a new era for CSS. Historically, CSS has been a declarative, relatively rigid language. This update brings it closer to the flexibility of traditional programming, reducing reliance on preprocessors or external scripts. It’s a direct response to developer needs, making stylesheets more expressive and robust.

Takeaway: A Dynamic Future for CSS

Inline conditional logic with if() empowers developers to build smarter, more adaptable, and concise stylesheets. While browser support is still evolving, this feature is set to become an essential tool in the web developer’s arsenal, enabling dynamic UI logic without ever leaving CSS.

Source: The New Stack