Exploring the :has() Selector in CSS

CSS has progressed greatly over time, introducing a number of advanced selectors that improve the ability to style web pages with precision and flexibility. One of the most recent additions to the CSS selector is the :has() pseudo-class. This blog will go over the details of the :has() selector, including its usage, benefits, and practical examples to help you use this powerful tool in your web development projects.

What is the :has() Selector?

The :has() selector is a relational pseudo-class that lets you choose an element depending on the presence of a descendant or a more complicated relationship within its subtree. In simpler terms, it allows you to style a parent element if it contains specific child components.(Read more Example of CSS :has)

Syntax:

element:has(selector) {
  /* CSS properties */
}

Key Features

Relational Selection: Unlike typical CSS selectors, which focus on the element or its immediate children, :has() selector looks at the content within the element to see if it fits a specified conditions.
Dynamic Styling: It can dynamically apply styles based on the presence or absence of specific elements, resulting in more interactive and context-aware designs.

Practical Examples of :has() Selector :

Parent Highlight on Child Focus using :has Selector

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Parent Highlight on Child Focus</title>
</head>
<body>
  <div class="container">
    <div class="highlight">
      <input type="text" placeholder="Focus me!">
    </div>
    <div class="highlight">
      <input type="text" placeholder="Or me!">
    </div>
  </div>
</body>
</html>

body {
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  background-color: #f5f5f5;
}

.container {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.highlight {
  padding: 10px;
  border: 2px solid transparent;
  border-radius: 4px;
  background-color: #fff;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.highlight:has(input:focus) {
  border-color: #007BFF;
  background-color: #e6f2ff;
}

input {
  width: 100%;
  padding: 8px;
  box-sizing: border-box;
  border: 1px solid #ddd;
  border-radius: 4px;
}

display: flex;: Applies Flexbox layout to the body element.
Learn more about display: Flex.
box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1); – Adds a shadow effect below the element with a slight blur and offset.
.highlight:has(input:focus) Selector:

border-color: #007BFF; – Changes the border color to a blue shade when any input inside the .highlight element is focused.

background-color: #e6f2ff; – When any input is focused inside the .highlight element, the background colour changes to a light blue.

Conclusion

The :has() selector is an extremely useful element in current CSS, allowing developers to construct more dynamic and context-aware styles. Understanding and utilising this selection allows you to improve the interactivity and visual attractiveness of your online projects while keeping the code clear and maintainable.

Experiment with the :has() selector in your projects to see how it can help simplify your CSS and create more advanced styling results. As browser support improves, the :has() selector is poised to become a key tool in the toolkit of web developers.