It is recommended to use the <link> tag to load CSS files for the following reasons: 1. The loading order is different, the parallel loading of <link> increases the speed, and the serial loading of @import causes delays; 2. The <link> is more compatible and easier to maintain, especially in old browsers and multi-person collaboration scenarios; 3. <link> supports performance optimization methods such as preload, but @import cannot participate in such optimizations.

There are two main ways to load CSS files: @import and <link> tags. Although both can introduce style sheets to web pages, their behavior and performance are significantly different in actual use.

To put it directly, the key point is: it is recommended to use the <link> tag to load CSS files instead of @import . The reasons are mainly focused on loading performance, browser compatibility and maintainability.

1. The loading order is different, which affects the rendering speed of the page

The <link> tag is loaded in parallel, that is, the browser will simultaneously download multiple CSS files introduced through <link> during the process of parsing HTML.

@import is a serial loading mechanism, which must wait until the main style sheet is loaded before requesting the imported style sheet. This can cause additional delay, especially when using @import nested, the page may have obvious "stylized moments".

For example:

 /* styles.css */
@import url('theme.css');

The browser will first load styles.css and then load theme.css . If you introduce these two files with two <link> tags, downloading will start at the same time.

2. Compatibility and maintainability differences

Although modern browsers basically support @import , it behaves inconsistently in some older browsers (such as IE5-IE8) and may even be ignored. If you need to consider the support of older browsers, <link> appears to be more reliable.

In addition, from the perspective of code maintenance, too much @import nesting can easily cause structural confusion, especially when multi-person collaborative development, it is not easy to quickly locate the style source. In contrast, <link> is written directly in HTML, which is clear and convenient for debugging and management.

3. Impact on page performance

Use <link> to better utilize the browser's preloading mechanism, for example, you can load critical CSS files in advance by setting rel="preload" :

 <link rel="preload" href="critical.css" as="style" onload="this.rel=&#39;stylesheet&#39;">

This optimization method is very useful for improving the loading speed of the first screen, and @import is almost unable to participate in this type of advanced optimization.

Let’s summarize a few key points:

• <link> is loading in parallel, faster; @import is loading in serial, slower.
• <link> supports more optimization methods, such as preload, media query, etc.
• <link> is more conducive to team collaboration and maintenance.
• @import is mainly used to organize modular styles in CSS files, but is not the preferred loading method.

Basically that's it. Unless you have a special reason to use @import (such as organization internal style modules), it is recommended to use the <link> tag to load CSS files first.

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