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HTML

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HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

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CSS

About CSS Preprocessors

CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

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About Vendor Prefixing

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JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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Packages

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HTML 

              
                <section>
  writing-mode: 
  <select id="writing-mode">
    <option value="horizontal-tb">horizontal-tb</option>
    <option value="vertical-lr">vertical-lr</option>
    <option value="vertical-rl">vertical-rl</option>
  </select>
</section>

<section id="content">
  <p>水陆草木之花，可爱者甚蕃。晋陶渊明独爱菊。自李唐来，世人甚爱牡丹。予独爱莲之出淤泥而不染，濯清涟而不妖，中通外直，不蔓不枝，香远益清，亭亭净植，可远观而不可亵玩焉。</p>
  <p>予谓菊，花之隐逸者也；牡丹，花之富贵者也；莲，花之君子者也。噫！菊之爱，陶后鲜有闻。莲之爱，同予者何人？牡丹之爱，宜乎众矣。</p>
  <p>水上、陆地上各种草本木本的花，值得喜爱的非常多。晋代的陶渊明只喜爱菊花。从李氏唐朝以来，世上的人十分喜爱牡丹。而我唯独喜爱莲花从淤泥中长出却不被污染，经过清水的洗涤却不显得妖艳。它的茎内空外直，不生蔓不长枝，香气远播更加清香，笔直洁净地立在水中。人们只能远远地观赏而不能靠近赏玩它啊。</p>
  <p>我认为菊花，是花中的隐士；牡丹，是花中的富贵者；莲花，是花中品德高尚的君子。唉！对于菊花的喜爱，陶渊明以后就很少听到了。对于莲花的喜爱，像我一样的还有什么人呢？对于牡丹的喜爱，当然就很多人了！</p>
</section>
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CSS 

              
                p {
  margin: 50px 100px;
}
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JS 

              
                document.querySelector('#writing-mode').addEventListener('change', event => {
  document.querySelector('#content').style.writingMode = event.target.value;
})
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999px

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