應(yīng)避免在CSS文件中使用@import，因為它會降低網(wǎng)站加載速度並增加維護(hù)難度。 1. 它阻止並行下載，瀏覽器必須先加載主樣式表才能開始下載導(dǎo)入的樣式表，從而延長關(guān)鍵渲染路徑；2. 維護(hù)和調(diào)試?yán)щy，嵌套導(dǎo)入使樣式來源不易追蹤；3. 更好的替代方案包括使用<link>標(biāo)籤、構(gòu)建時合併CSS、使用CSS預(yù)處理器模塊化功能；4. 雖然在特定場景如打印樣式有條件加載時仍可用，但多數(shù)情況下應(yīng)謹(jǐn)慎使用。

You should avoid using @import in your CSS files mainly because it can slow down your website's loading speed and complicate maintenance. While it might seem convenient for organizing styles, the performance trade-offs usually aren't worth it.

It Blocks Parallel Downloads

Modern browsers download CSS files in parallel to speed things up. But when you use @import , the browser has to load the main stylesheet first before it even starts downloading the imported ones. This adds extra time to the critical rendering path.

For example:
If you have a main.css file that uses @import to pull in reset.css and layout.css, the browser won't start downloading reset.css or layout.css until after main.css is fully downloaded and parsed.

This creates a chain of dependencies and delays page rendering.

It's Harder to Maintain and Debug

Using @import can make your CSS structure less transparent. When styles are spread across multiple nested imports, tracking down where a particular style is coming from becomes more difficult.

Also:

• Build tools and preprocessors (like Sass) often handle modular CSS better with their own features.
• If someone else works on your code later, they may not expect styles to be buried deep in imported files.

Better Alternatives Are Available

Instead of @import , consider these modern approaches:

• Use <link> tags: Browsers can download multiple CSS files independently if you include them directly in your HTML with separate <link> tags.
• Concatenate CSS during build: Tools like Webpack, Gulp, or PostCSS can combine your CSS files into one during deployment, reducing HTTP requests without sacrificing organization.
• Use CSS variables and partials (with preprocessors): If you're using Sass or Less, take advantage of partials and mixins to keep your CSS modular and clean.

These methods offer better performance and clearer structure.

Not Completely Obsolete (But Use With Caution)

There are some edge cases where @import still makes sense — like conditionally loading print styles or applying media queries inside a stylesheet. For example:

 @import url('print.css') print;

This tells the browser to only load print.css when printing the page. But even here, using a separate <link> tag with a media attribute achieves the same thing more efficiently.

So while @import isn't always bad, it's best avoided in most situations where performance and clarity matter.

基本上就這些。

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