Why use selectors

The reason for using selectors is to accurately select the elements that need to be styled, implement style inheritance and reuse, control the cascading and priority of styles, and implement responsive layout and adapt to different devices. Detailed introduction: 1. Accurately select elements that need to be styled. HTML documents usually contain a large number of elements, and their structures and hierarchical relationships are complex and diverse. Use selectors to select elements based on their tag names, class names, IDs and other attributes. Select specific elements to avoid the tedious work of manually adding styles to each element; 2. Implement style inheritance and reuse, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Selector is an important concept in CSS (Cascading Style Sheets), which is used to select specific elements in an HTML document and apply styles to them. The function of selectors is to associate styles with HTML elements, so that we can control the appearance and behavior of elements through selectors. Selectors are an essential tool when writing CSS stylesheets.

First of all, selectors can help us accurately select the elements that need to be styled. HTML documents usually contain a large number of elements, and their structures and hierarchical relationships are complex and diverse. Use selectors to select specific elements based on their tag name, class name, ID and other attributes, thus avoiding the tedious work of manually adding styles to each element. For example, we can use a class selector to select all elements with the same class name and apply the same style to them, which can greatly improve the efficiency of style writing.

Secondly, selectors can help us realize style inheritance and reuse. Style rules in CSS style sheets can be applied to multiple elements through selectors, thereby enabling style inheritance and reuse. For example, we can use the descendant selector to select the descendant elements of an element and apply the same style to them. In this way, when we need to modify the style, we only need to modify one piece of code instead of modifying the style of each element one by one.

In addition, selectors can also help us achieve style cascading and priority control. When multiple style rules are applied to the same element, the selector can determine the final style to be applied based on the specificity and priority of the rules. In this way, we can control the cascading order and priority of styles through the flexible use of selectors, thereby achieving more precise style control.

Finally, selectors can also help us implement responsive layout and adapt to different devices. In modern web development, responsive layout has become an important design concept. The selector can select different style rules based on different media query conditions to achieve adaptation and responsive layout on different devices. In this way, we can implement a website that adapts to different screen sizes and devices through the flexible use of selectors.

To sum up, the selector is an important concept in CSS. It can help us accurately select the elements that need to be styled, realize the inheritance and reuse of styles, control the cascading and priority of styles, and implement responsiveness. layout and adapt to different devices. The use of selectors can greatly improve the efficiency and flexibility of style writing, allowing us to better control and customize the appearance and behavior of HTML elements. Therefore, selectors are an indispensable tool in CSS writing.

The above is the detailed content of Why use selectors. For more information, please follow other related articles on the PHP Chinese website!