DEV Community

MechCloud Academy profile image Akash
Akash for MechCloud Academy

Posted on

CSS Nesting and Its Potential to Replace CSS Preprocessors Like SCSS and SASS

#css

Introduction to CSS Nesting

CSS nesting is a native CSS feature that allows you to nest selectors within one another, creating a hierarchical structure that mirrors the HTML document. This eliminates the need to repeat parent selectors, making stylesheets more concise and easier to read. For years, developers relied on CSS preprocessors like SCSS (Sassy CSS) and SASS (Syntactically Awesome Style Sheets) to achieve this functionality. However, with the introduction of native CSS nesting in 2023, supported by all major browsers (Chrome/Edge 112+, Firefox 117+, Safari 16.5+), developers can now achieve similar results without external tools.

Why CSS Nesting Matters

  • Improved Readability: Nested selectors group related styles, reducing visual clutter.
  • Reduced Repetition: No need to repeat parent selectors for child elements.
  • Native Browser Support: Eliminates dependency on preprocessors, simplifying build processes.
  • Maintainability: Nested structures make it easier to update styles for related elements.

How CSS Nesting Works

CSS nesting allows you to write child selectors inside a parent selector block using curly braces {}. The nested selectors are automatically scoped to the parent, and the & symbol (nesting selector) can be used to reference the parent explicitly for pseudo-classes, pseudo-elements, or combinators.

Basic Syntax 

.parent {
  color: blue;
  .child {
    font-size: 16px;
  }
}
Enter fullscreen mode Exit fullscreen mode

This compiles to:

.parent {
  color: blue;
}
.parent .child {
  font-size: 16px;
}
Enter fullscreen mode Exit fullscreen mode

Using the & Nesting Selector

The & symbol represents the parent selector and is useful for:

  • Pseudo-classes: &:hover
  • Pseudo-elements: &::before
  • Combinators: &.active
  • Sibling selectors: & + .sibling

Example:

.button {
  background: navy;
  &:hover {
    background: darkblue;
  }
  &.active {
    border: 2px solid gold;
  }
  &::before {
    content: '★';
  }
}
Enter fullscreen mode Exit fullscreen mode

Nesting with Media Queries

CSS nesting also supports nested media queries, allowing responsive styles to be grouped within the same block:

.container {
  width: 100%;
  @media (min-width: 768px) {
    width: 80%;
    .inner {
      padding: 20px;
    }
  }
}
Enter fullscreen mode Exit fullscreen mode

Comparing CSS Nesting to SCSS/SASS

SCSS and SASS have long been popular for their nesting capabilities, along with features like variables, mixins, functions, and partials. Let’s compare CSS nesting to SCSS/SASS and evaluate whether it can replace them.

Similarities

  • Nesting Syntax: Both CSS nesting and SCSS/SASS allow hierarchical selector nesting, reducing repetition.
  • Parent Selector (&): SCSS/SASS use & similarly to reference the parent selector.
  • Readability: Both improve stylesheet organization by grouping related styles.

Differences

  1. Variables:
    • SCSS/SASS: Support variables (e.g., $primary-color: #007bff;) for reusable values.
    • Native CSS: Offers custom properties (e.g., --primary-color: #007bff;), which are dynamic and can be manipulated with JavaScript.
  2. Mixins:
    • SCSS/SASS: Allow reusable style blocks (e.g., @mixin flex-center { display: flex; ... }).
    • Native CSS: Lacks mixins, but custom properties and utility classes (e.g., Tailwind CSS) can achieve similar results.
  3. Functions and Loops:
    • SCSS/SASS: Support complex logic like loops and color functions.
    • Native CSS: Limited to calc(), min(), max(), and other basic functions, with no looping capabilities.
  4. Partials and Imports:
    • SCSS/SASS: Allow splitting code into partials (e.g., _base.scss) and importing them.
    • Native CSS: Supports @import, but it’s less efficient and lacks partials.
  5. Build Process:
    • SCSS/SASS: Require a build step to compile to CSS, adding complexity.
    • Native CSS: No compilation needed, simplifying workflows.

Can CSS Nesting Replace SCSS/SASS?

CSS nesting covers the core functionality of preprocessor nesting, and with modern CSS features like custom properties, container queries, and cascade layers, it addresses many use cases that once required preprocessors. However, SCSS/SASS still offer advantages in complex projects requiring mixins, loops, or modular file structures. For small to medium projects, or those prioritizing simplicity, native CSS nesting can often suffice, especially when paired with modern frameworks like Tailwind CSS or utility-first approaches.

Practical Examples of CSS Nesting

Let’s build a sample project to demonstrate CSS nesting in action, creating a card component with hover effects, responsive design, and nested elements.

Example: Card Component 

.card {
  background: white;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  padding: 16px;
  transition: transform 0.2s;

  &:hover {
    transform: translateY(-4px);
  }

  .title {
    font-size: 1.5rem;
    color: #333;
    margin-bottom: 8px;
  }

  .content {
    font-size: 1rem;
    color: #666;
    line-height: 1.5;
  }

  .button {
    background: #007bff;
    color: white;
    padding: 8px 16px;
    border-radius: 4px;
    text-decoration: none;

    &:hover {
      background: #0056b3;
    }
  }

  @media (max-width: 600px) {
    padding: 12px;
    .title {
      font-size: 1.25rem;
    }
  }
}
Enter fullscreen mode Exit fullscreen mode

Corresponding HTML:

<div class="card">
  <h2 class="title">Card Title</h2>
  <p class="content">This is the card content.</p>
  <a href="#" class="button">Learn More</a>
</div>
Enter fullscreen mode Exit fullscreen mode

This example showcases:

  • Nested selectors for .title, .content, and .button.
  • Use of & for hover states.
  • Nested media queries for responsive design.
  • Clean, maintainable structure without preprocessor dependencies.

Example: Navigation Menu 

.nav {
  display: flex;
  gap: 16px;
  padding: 16px;
  background: #f8f9fa;

  .nav-item {
    text-decoration: none;
    color: #333;
    font-weight: 500;

    &:hover {
      color: #007bff;
    }

    &.active {
      color: #007bff;
      border-bottom: 2px solid #007bff;
    }
  }

  @media (max-width: 768px) {
    flex-direction: column;
    gap: 8px;
  }
}
Enter fullscreen mode Exit fullscreen mode

This demonstrates nesting for a responsive navigation menu, with active and hover states, all within a single block.

Best Practices for CSS Nesting

To use CSS nesting effectively and avoid pitfalls, follow these best practices:

  1. Limit Nesting Depth: Avoid nesting more than 3–4 levels to prevent overly specific selectors, which can reduce performance and maintainability. 
   /* Bad: Too deep */
   .parent {
     .child {
       .grandchild {
         .great-grandchild {
           color: blue;
         }
       }
     }
   }
   /* Good: Shallow nesting */
   .parent .child {
     color: blue;
   }
Enter fullscreen mode Exit fullscreen mode
  1. Use & Judiciously: Only use & when necessary (e.g., for pseudo-classes or combinators) to keep code clean.
  2. Combine with Custom Properties: Use CSS custom properties for reusable values: 
   :root {
     --primary: #007bff;
   }
   .button {
     background: var(--primary);
     &:hover {
       background: darken(var(--primary), 10%); /* Fallback to SCSS if needed */
     }
   }
Enter fullscreen mode Exit fullscreen mode
  1. Test Browser Compatibility: Use @supports selector(&) for fallbacks: 
   @supports selector(&) {
     .parent {
       .child {
         color: blue;
       }
     }
   }
   @supports not selector(&) {
     .parent .child {
       color: blue;
     }
   }
Enter fullscreen mode Exit fullscreen mode
  1. Organize with Cascade Layers: Use @layer to manage specificity and avoid conflicts: 
   @layer base {
     .component {
       .child {
         color: blue;
       }
     }
   }
Enter fullscreen mode Exit fullscreen mode

Limitations of CSS Nesting

While powerful, CSS nesting has limitations compared to SCSS/SASS:

  • No Mixins or Loops: You can’t define reusable style blocks or iterate over values.
  • No File Splitting: Native CSS lacks partials, making large projects harder to organize.
  • Limited Functions: CSS functions are less robust than SCSS’s color manipulation or math utilities.
  • Specificity Issues: Deep nesting can lead to high specificity, complicating overrides.

To mitigate these, consider:

  • Using utility-first CSS frameworks (e.g., Tailwind) for reusable styles.
  • Organizing large projects with cascade layers or BEM methodology.
  • Leveraging modern CSS features like clamp() or color-mix() for dynamic styling.

When to Stick with SCSS/SASS

While CSS nesting is robust, SCSS/SASS may still be preferable for:

  • Complex Projects: Large teams or codebases benefit from partials, mixins, and modular imports.
  • Advanced Logic: Loops, conditionals, or complex color functions are exclusive to preprocessors.
  • Legacy Codebases: Existing SCSS/SASS projects may not justify a rewrite.
  • Team Familiarity: Teams accustomed to SCSS/SASS may prefer its ecosystem.

Conclusion

CSS nesting, combined with modern CSS features like custom properties, container queries, and cascade layers, offers a compelling alternative to SCSS and SASS for many projects. It simplifies workflows by eliminating the need for build tools, reduces dependencies, and provides a native, browser-supported way to write clean, hierarchical styles. For small to medium projects, or those prioritizing simplicity, CSS nesting can often replace preprocessors entirely. However, for complex applications requiring advanced logic, modular file structures, or legacy support, SCSS/SASS remain valuable.

By mastering CSS nesting and following best practices, developers can write efficient, maintainable stylesheets that leverage the full power of modern CSS. As browser support continues to solidify (95%+ global coverage as of 2025), CSS nesting is poised to become a cornerstone of web development, challenging the dominance of preprocessors and empowering developers to build better, faster, and simpler.

Further Resources

Top comments (0)