2R - CSS Nesting

Summary

CSS nesting is a feature that allows developers to write cleaner, more organized style rules by placing child selectors inside parent selectors—similar to SCSS or other preprocessor syntax. This improves readability and makes styles easier to maintain, especially for components or repeated UI structures.

Origins of CSS Nesting

CSS nesting originated as a popular feature in CSS preprocessors like Sass (SCSS), which let developers write nested rules to avoid repetitive selectors. This idea influenced the official CSS Working Group to explore and eventually implement native nesting as part of the CSS standard. As of 2023, CSS nesting is now being implemented natively in major browsers.

The Ampersand (&) Selector

The ampersand & is used inside nesting blocks to reference the parent selector. It’s especially helpful for adding modifier classes or pseudo-classes like &:hover or &.active, without having to repeat the full selector name. This keeps code DRY and easier to read.

Browser Support

According to Can I use, native CSS nesting is supported in the latest versions of Chrome, Edge, Safari, and Firefox (as of version 117+). However, it may still require enabling a flag or using a build tool like PostCSS for broader compatibility in older browsers.

Example of CSS Nesting

HTML

                    <div class="card">
                        <h2>Hello World</h2>
                        <button>Click Me</button>
                    </div>

CSS

                    .card {
                        background-color: #f0f0f0;
                        padding: 1rem;
                        border-radius: 8px;

                        h2 {
                            color: #004466;
                        }

                        button {
                            background-color: #007acc;
                            color: white;
                            border: none;
                            padding: 0.5rem 1rem;
                            border-radius: 4px;

                            &:hover {
                            background-color: #005fa3;
                            }
                        }
                    }

Description

In this example, the .card class styles a container. Nested inside it are rules for h2 and button elements. The button also includes a nested :hover selector using the ampersand & to apply hover styles only when the button is hovered inside a .card.

How I Would Use Nesting in a Project

I would use nesting in component-based designs to keep related styles together. For example, in a navigation bar, I could nest ul, li, and a:hover styles under a .navbar class. This improves organization and avoids repeating long selectors across the stylesheet.

AI Disclaimer and Citation

This content was created using generative AI.

Citation:
"Please document and research the concept of CSS Nesting. Please provide a summary of it. I also need the summaries for the origins of css nesting, how the ampersand is used a a nesting selector, and a summary for browser support based on data from caniuse.com. Please then also create an example for the HTML, CSS using CSS nesting, and the nesting selector ampersand. For these examples, describe what on the demo page is being styled by the CSS nesting code. How the ampersand was used as a nesting selector. Finally how I would use nesting in a project. Thanks." prompt. ChatGPT, GPT-4, OpenAI, 04 Apr. 2025, https://chat.openai.com/.