要減少CSS文件大小，首先移除未使用的CSS代碼，其次對(duì)CSS進(jìn)行壓縮和最小化處理，接著使用高效的CSS選擇器并避免冗余樣式，最后優(yōu)化關(guān)鍵CSS以加快首屏加載速度。通過(guò)工具如PurgeCSS或UnCSS可有效刪除無(wú)用代碼，有時(shí)能減少50%以上的文件體積；使用CSSNano或構(gòu)建工具如Webpack進(jìn)行最小化，并啟用Gzip或Brotli壓縮，可進(jìn)一步減小傳輸體積；采用類選擇器而非復(fù)雜選擇器、復(fù)用共享類可提升性能與維護(hù)性；對(duì)性能敏感的站點(diǎn)還可提取并內(nèi)聯(lián)關(guān)鍵CSS，延遲加載其余樣式，從而顯著提升頁(yè)面加載速度。

There’s no one-size-fits-all way to reduce CSS file size, but the good news is, there are several straightforward methods that work well together. The key is to focus on efficiency without sacrificing maintainability or design quality.

1. Remove Unused CSS

One of the biggest contributors to bloated CSS files is unused code. This often happens when you're working with large frameworks like Bootstrap or when styles are left behind after redesigns.

• Use tools like PurgeCSS or UnCSS to scan your HTML and remove unused selectors.
• Be cautious with single-page apps or dynamic sites—make sure the tool covers all possible states and routes.
• If you're using a CSS framework, consider importing only the components you actually use, instead of the entire stylesheet.

This step alone can cut file size by 50% or more, especially in larger projects.

2. Minify and Compress Your CSS

Minifying CSS means removing unnecessary characters like spaces, comments, and line breaks. It’s a standard optimization step and very effective.

• Use tools like CSSNano, PostCSS, or build tools like Webpack, Gulp, or Parcel to automate minification.
• Enable Gzip or Brotli compression on your server. These compression methods can reduce CSS file size by up to 70% before it even hits the browser.

You don’t have to do this manually—most modern build setups handle it by default.

3. Use Efficient Selectors and Avoid Redundancy

CSS performance isn’t just about file size; it’s also about how efficiently the browser can parse and apply styles.

• Avoid overly specific selectors like div#main-content ul.menu li.active.
• Stick to class-based selectors (e.g., .btn-primary) which are both fast and flexible.
• Don’t repeat styles unnecessarily—use shared classes instead of writing the same styles over and over.

This helps not only with file size but also with rendering performance and maintainability.

4. Optimize for Critical CSS (Advanced but Worth It)

If you're optimizing for speed, especially for initial page load, inlining critical CSS can help.

• Extract and inline only the styles needed for the above-the-fold content.
• Load the rest of the CSS asynchronously or defer it.
• Tools like Critical CSS or Penthouse can help automate this process.

It’s a bit more complex and best suited for performance-critical sites, but it makes a real difference in load times.

基本上就這些。Reducing CSS file size is more about smart cleanup and automation than rewriting everything from scratch. Do a little pruning, automate the rest, and your site will load faster without losing style.

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