THe :where Pseudo-Class

Introduction

The “:where” pseudo-class is an experimental feature that is currently being proposed for the CSS Selectors Level 4 specification. It is similar to the “:is” pseudo-class, but it provides even more flexibility by allowing you to style elements based on the state of their siblings or children.

The basic syntax for the “:where” pseudo-class is as follows:

element:where(sibling-selector) {
    /* styles */
}

/* or */

element:where(child-selector) {
    /* styles */
}

Advantages

One of the main advantages of using the “:where” pseudo-class is that it allows you to apply styles to an element based on the state of other elements in the same document. For example, you can use the “:where” pseudo-class to change the styling of a label element when a corresponding checkbox is checked:

label:where(input[type="checkbox"]:checked) {
    text-decoration: underline;
}

This code will select all label elements that have a corresponding checkbox that is checked and apply text-decoration: underline to those labels. This can make it easy to create complex interactions with a minimal amount of CSS.

In summary, the “:where” pseudo-class is a proposed feature that provides powerful styling capabilities by allowing you to style elements based on the state of their siblings or children. It provides great flexibility and can make it easy to create complex interactions, but it’s important to keep in mind that it is currently experimental and not widely supported. As a developer, it’s important to be aware of new features like this and to be ready to use them when they become more widely adopted.