CSS if() Function: Conditional Logic in Modern Styling

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CSS IF()

CSS if() Function

Conditional logic is no longer just for programming languages—CSS now has its own if() function! With this, modern web styling becomes more dynamic, maintainable, and readable, especially for large business websites and complex design systems. Whether you’re a student, seasoned developer, or business leader seeking adaptable design without technical debt, the CSS if() function brings transformative potential to your workflow. 1
WHAT

What is the CSS if() Function?

The CSS if() function empowers developers to apply conditional logic directly within CSS property values—much like an inline if-else statement in languages like JavaScript, but tailored for the declarative style of CSS. This means you can solve use cases (like responsive sizing or feature toggling) without scattering logic across separate rule blocks or massive media query bundles 2
CODE

Basic Structure

The basic syntax is as follows:
styles.css
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property: if(condition-1: value-1; condition-2: value-2; else: fallback);
  • Each pair
    checks a condition and provides a value.
  • The first matched condition
    returns its value for the property.
  • Else
    provides a fallback if none of the conditions are met.
Supported Condition Types
  • style()
    Queries for custom property values or computed styles.
  • media()
    Inline media queries for responsiveness.
  • supports()
    Checks for CSS feature support.
EXAMPLE
Example:

Responsive button width:

This sets width to 30px for mouse users (fine pointer) and 44px for touch devices, improving usability.

styles.css
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button {
  width: if(media(any-pointer: fine): 30px; else: 44px);
}
DIFFERENT

How is if() Different from Previous CSS Solutions?

With if(), you manage all conditions for a property in one spot, reducing redundancy and easing future updates. 3
Feature @media Queries if() Function
Logic Location Separate blocks Inline, property-specific
Maintainability Spread across files Centralized per property
Learning Curve Familiar to most New, but programming-like
Browser Support Universal Modern Chromium browsers
Responsive Design (Media Queries)
Adjusting layout for desktop vs. mobile. This collapses your sidebar on small screens for a better mobile experience.
styles.css
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.sidebar {
  width: if(media(min-width: 768px): 300px; else: 100%);
}
Theming with Custom Properties
Dynamic theme switching based on variable settings. 4

If --variant is set, use the primary color; otherwise default to white.
styles.css
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.card {
  background: if(style(--variant): var(--primary); else: white);
}
USE CASES

Real-World Use Cases

Feature Detection (@supports)
Use a modern property if available, otherwise fallback. No more duplicated blocks for progressive enhancement—if() puts all your logic front and center.
styles.css
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.button {
  aspect-ratio: if(supports(aspect-ratio: 1): 1; else: auto);
}
Dynamic Color Schemes
Change UI colors based on user’s color setting. 5

Adapts automatically when the scheme changes—think dashboards that theme themselves.
styles.css
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:root {
  --scheme: dark;
}
h1 {
  color: if(style(--scheme: dark): #fff; style(--scheme: light): #000; else: #555);
}
Conditional Pseudo-content
Add or swap icons depending on user status or settings. Give your business dashboard that finishing touch without extra JavaScript.
styles.css
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.user-status::before {
  content: if(style(--admin): "👑 "; style(--vip): "⭐ "; else: "● ");
}
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PROS & CONS
Should You Use if() Now?

Pros and Cons

Pros
  • Dramatically reduces code duplication
  • Eases maintainability
  • Enables truly dynamic styling for business apps and SaaS platforms
  • Integrates deeply with modern CSS methodologies and design systems
Cons
  • Limited browser support: Late 2025, only in Chrome 137+ and Chromium-based browsers
  • The new syntax requires a mindset shift for some teams
  • May need progressive enhancement for broad audiences
Pro Tip
For now, combine if() with existing robust CSS features for the best of both worlds.
BEST PRACTICES

Best Practices & SEO/Business Impact

With the CSS if() function, you’re not just styling websites—you’re building a future where business logic and design work seamlessly, intuitively, and beautifully together.

  • Keep logic readable
    Don’t pile on too many conditions at once.
  • Progressive enhancement
    Always set sensible else fallbacks for older browsers.
  • Centralize theming
    Use design tokens with style() to streamline company-wide UI updates.
  • Improve accessibility
    Fine-tune styles dynamically for different input types and environments.
  • Optimize for generative/LLM SE
    : Clear, conditional logic aids both automated documentation and content extraction for AI summarizers and search.

Simple things should be simple, complex things should be possible.

Alan Kay

Thank You for Spending Your Valuable Time

I truly appreciate you taking the time to read blog. Your valuable time means a lot to me, and I hope you found the content insightful and engaging!
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FAQ's

Frequently Asked Questions

Not completely. if() offers inline conditionals for properties, but full-layout queries might still use @media for now. Use both for the best results until support is universal.

Currently, if() is supported in Chrome 137+ and other Chromium-based browsers. Always test or provide fallbacks for critical layouts.

For most uses, performance is unaffected—conditional checks are already a part of how browsers parse and compute CSS. However, large and complex rules may need profiling in mission-critical sites.

Yes! Cleaner logic, truly responsive features, and new design possibilities all help business sites deliver a more personalized, dynamic user experience.

Start by refactoring small, isolated properties—especially where inline conditionals reduce duplication. Test with progressive enhancement until support grows. Use design tokens for smooth transitions.

Blogs

Related Blogs

  1. Available at: https://developer.chrome.com/blog/if-article
  2. Available at: https://blog.logrocket.com/css-if-function-conditional-styling-2025/
  3. Available at: https://www.amitmerchant.com/the-if-function-in-css/
  4. Available at: https://www.amitmerchant.com/the-if-function-in-css/
  5. Available at: https://css-tricks.com/poking-at-the-css-if-function-a-little-more-conditional-color-theming/

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