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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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About the <head>

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Insecure Resource

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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

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

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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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You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

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Using packages here is powered by esm.sh, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ESM usage.

All packages are different, so refer to their docs for how they work.

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HTML 

              
                <div class="wrapper container">
  <h1>Example page</h1>
  
  <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Cumque, voluptate corrupti nam adipisci ad enim accusantium iusto distinctio non fugiat esse. Fugiat neque enim pariatur voluptas numquam nemo dolorum doloribus.</p>
  
  <p>Lorem ipsum dolor, sit amet consectetur adipisicing elit. Nisi itaque aut inventore ratione quasi explicabo consequatur laboriosam temporibus, illo architecto reiciendis dignissimos pariatur facilis, neque officiis doloremque doloribus. Minima, blanditiis!</p>
  <p>Laborum molestias aspernatur quibusdam ex officia ad eos a soluta et assumenda, odit sequi ipsa, maiores provident fugit similique animi harum aut minima. Ut autem pariatur facilis eligendi veritatis sequi!</p>
  <p>Eos nemo nisi facere quisquam nostrum commodi ab illo labore atque sed, neque quidem molestias facilis accusantium doloribus doloremque temporibus. Autem natus, libero minima vero quod quaerat voluptatum accusamus quasi?</p>
  <p>Quasi, in rerum omnis fugit ducimus commodi error quia hic harum obcaecati repudiandae totam asperiores, accusamus sapiente laboriosam veniam odio soluta ea quis distinctio. Libero illum repellendus ratione placeat odio!</p>
  <p>In voluptates quos quas delectus, voluptatibus itaque a tenetur magni fuga vero maxime sint eveniet rem, quis eaque optio eius repudiandae ratione dicta totam? Id consequatur quaerat suscipit a rerum.</p>
  <p>Facere aliquam ea tenetur earum molestiae! Earum quod sunt est rerum ipsa ut? Autem quas obcaecati porro ipsum eum quibusdam, cupiditate doloribus omnis, cum corporis itaque, ex ut iusto modi.</p>
</div>

<div class="modal">
  <div class="modal-inner container">
    <h3>Modal</h3>
    
    <p>After a 1s delay, <code>.modal</code> (and contents) fade-in using a basic CSS animation. This uses no JS or jQuery.</p>
  </div>
</div>
!

CSS 

              
                html {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  background: #F6D0BF;
  font-size: 18px;
  line-height: 1.4;
}

.wrapper {
  max-width: 820px;
  margin: auto;
}
.container {
  padding: 1em;
}

.block {
  display: inline-block;
  margin: 1em 10%;
  width: 30%;
  height: 100px;
}

// Modal animation
@keyframes fadein {
  from { opacity: 0; }
  to { opacity: 1; }
}

// Modal styling
.modal {
  background: rgba(225, 239, 202, 0.7);
  display: flex;
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  z-index: 20;
  opacity: 0;
  
  // Animation trigger  
  animation: fadein 1s;
  animation-delay: 1s;
  animation-fill-mode: forwards;
}
.modal-inner {
  background: rgb(225, 239, 202);
  color: black;
  border: 2px dashed white;
  margin: auto; // Centres the element vertically & horizontally due
  max-width: 320px;
  text-align: center;
  font-size: 16px;
}
!

JS
!
999px

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