CSS Nesting: Concept and Origins

CSS Nesting allows developers to write cleaner, more modular, and maintainable stylesheets by nesting one style rule inside another. This approach reduces the need to repeat selectors for related elements, making the CSS code class="language-css" more readable and potentially reducing file size.

Origins of CSS Nesting

CSS nesting has its roots in CSS preprocessors like Sass and Less, which have long supported nested syntax to simplify complex stylesheets. However, native CSS nesting is different because it is parsed directly by the browser rather than being pre-compiled by a preprocessor. This shift towards native support aims to streamline the development process and improve performance.

The Ampersand (&) as a Nesting Selector

The ampersand (&) is a crucial part of CSS nesting. It explicitly states the relationship between parent and child rules, making the nested child rule selectors relative to the parent element. Here are some key points about using the ampersand:

• Basic Nesting: The ampersand can be used to join selectors together, such as compound selectors or pseudo-classes.

      .parent {
        & .child {
            /* styles for child elements within parent */
        }
      }
      

• Pseudo-Classes: It helps in positioning the parent selector directly next to pseudo-classes without repetition.

        .button {
            &:hover {
                /* styles for button on hover */
            }
        }
      

• Combinators: The ampersand can be used with combinators like >, +, and ~ to create more specific selectors.

        .button {
            & > span {
                /* styles for direct child span */
            }
        }
      

Browser Support for CSS Nesting

According to Can I use, CSS nesting has gained significant support across major browsers since December 2023. Here is a summary of the current browser support:

CSS Nesting Example

Below is an example of HTML and CSS using CSS nesting and the nesting selector ampersand:

What's Being Demonstrated:

1. Basic button styling using CSS nesting
2. The ampersand (&) used in turn:
   • For states: &:hover and &:disabled
   • For variations: &.secondary, &.accent, and &.outline

CSS Nesting Code Example:

          .button {
            background-color: $primary-color;
            color: $light-gray;
            border: none;
            padding: $spacing-sm $spacing-lg;
            text-align: center;
            cursor: pointer;
            border-radius: $border-radius-md;
            font-family: $button-font;
            font-size: 16px;
            transition: all 0.3s ease;
          
            &:hover {
              background-color: $primary-darker;
            }
          
            &:disabled {
              background-color: $light-gray;
              color: $dark-gray;
              box-shadow: none;
              cursor: not-allowed;
            }
          
            // Secondary Button
            &.secondary {
              background-color: $secondary-color;
          
              &:hover {
                background-color: $secondary-darker;
              }
            }
          
            // Accent Button
            &.accent {
              background-color: $accent-color;
              color: $text-color;
          
              &:hover {
                background-color: $accent-darker;
              }
            }
          
            // Outline Button
            &.outline {
              background-color: transparent;
              border: 2px solid $border-color;
              color: $primary-color;
          
              &:hover {
                background-color: $primary-translucent;
              }
            }
          }