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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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Adding Classes

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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-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

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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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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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HTML 

              
                <main class="main">
  <section class="section">
    <h1>Hello World!</h1>
    <p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Voluptates officiis odio autem consequatur sequi non optio laborum inventore minima. Facilis quae deserunt quas dolorum accusantium aliquam? Delectus maiores omnis deserunt!</p>
  </section>
  <section class="section">
    <h2>Once upon a time...</h2>
    <p>Lorem, ipsum dolor sit amet consectetur adipisicing elit. Aliquid asperiores quibusdam exercitationem a expedita libero consequuntur officiis pariatur, molestiae ipsam est ratione consectetur dolore consequatur odio officia id, voluptatem amet?</p>
    <ul class="list">
      <li>The 1st Knight</li>
      <li>The 2nd Knight</li>
      <li>The 3rd Knight</li>
      <li>The 4th Knight</li>
      <li>The 5th Knight</li>
      <li>The 6th Knight</li>
      <li>The 7th Knight</li>
    </ul>
    <p>Aliquid dolores obcaecati quod, eligendi officiis minus aliquam quidem. Quibusdam blanditiis iure ratione maxime suscipit laborum, consectetur maiores vel, voluptate sit numquam minima placeat quis atque nostrum, asperiores vitae ab!</p>
    <p>Magni cupiditate dolores omnis saepe reprehenderit in porro, consequatur unde perspiciatis beatae, magnam maiores id distinctio harum, quod qui quia ex dolor officiis repellendus similique molestias blanditiis vel! Nam, cum?</p>
    <p>Fugiat similique debitis sequi a vero itaque quod suscipit quia qui excepturi ad nulla fuga quos nemo voluptatibus, eveniet ea omnis architecto. Esse, cupiditate excepturi molestiae perferendis laboriosam reiciendis quae.</p>
    <p>Exercitationem nobis eaque, placeat laborum vitae sunt reprehenderit ad omnis ipsum repellat iusto et corrupti enim possimus. Temporibus consequuntur voluptatum assumenda voluptatibus autem odit aliquam, tempora quas veritatis exercitationem nemo?</p>
    <p>Nihil, ea in? Asperiores corporis doloribus doloremque assumenda dignissimos. Quis quia et error dignissimos deserunt unde aspernatur reprehenderit? Nobis, labore laudantium iste assumenda ipsum quam nam minus cupiditate repellendus tempora!</p>
    <p>Delectus vel aspernatur repellendus tempora nobis odio eaque quod laborum amet, aliquid harum placeat quam, fugit architecto nostrum magni, nemo tenetur molestias. Veritatis atque, debitis ratione nesciunt ipsa recusandae ipsam.</p>
    <p>Eius odio placeat quidem porro fugit dolores, praesentium animi sit. Sunt, laboriosam illo iure pariatur, libero natus quo laudantium exercitationem optio totam, ratione maiores temporibus voluptate vitae in reiciendis perferendis!</p>
    <p>Eius ex, temporibus, provident natus accusamus, rerum illum perferendis quis eum minima culpa. Omnis accusamus, aut iusto perferendis rerum est, harum quo nisi, consequuntur in corrupti magni saepe culpa quisquam!</p>
    <p>Dolorum facilis rem earum nesciunt error doloremque excepturi sit incidunt nemo perferendis assumenda, animi et reprehenderit ea vero maiores aliquam totam distinctio neque alias debitis. Neque similique saepe obcaecati temporibus.</p>
  </section>
  <section class="section">
    <h2>The King and The Queen</h2>
    <p>Lorem, ipsum dolor sit amet consectetur adipisicing elit. Aliquid asperiores quibusdam exercitationem a expedita libero consequuntur officiis pariatur, molestiae ipsam est ratione consectetur dolore consequatur odio officia id, voluptatem amet?</p>
    <p>Aliquid dolores obcaecati quod, eligendi officiis minus aliquam quidem. Quibusdam blanditiis iure ratione maxime suscipit laborum, consectetur maiores vel, voluptate sit numquam minima placeat quis atque nostrum, asperiores vitae ab!</p>
    <p>Magni cupiditate dolores omnis saepe reprehenderit in porro, consequatur unde perspiciatis beatae, magnam maiores id distinctio harum, quod qui quia ex dolor officiis repellendus similique molestias blanditiis vel! Nam, cum?</p>
    <p>Fugiat similique debitis sequi a vero itaque quod suscipit quia qui excepturi ad nulla fuga quos nemo voluptatibus, eveniet ea omnis architecto. Esse, cupiditate excepturi molestiae perferendis laboriosam reiciendis quae.</p>
    <p>Exercitationem nobis eaque, placeat laborum vitae sunt reprehenderit ad omnis ipsum repellat iusto et corrupti enim possimus. Temporibus consequuntur voluptatum assumenda voluptatibus autem odit aliquam, tempora quas veritatis exercitationem nemo?</p>
    <p>Nihil, ea in? Asperiores corporis doloribus doloremque assumenda dignissimos. Quis quia et error dignissimos deserunt unde aspernatur reprehenderit? Nobis, labore laudantium iste assumenda ipsum quam nam minus cupiditate repellendus tempora!</p>
    <p>Delectus vel aspernatur repellendus tempora nobis odio eaque quod laborum amet, aliquid harum placeat quam, fugit architecto nostrum magni, nemo tenetur molestias. Veritatis atque, debitis ratione nesciunt ipsa recusandae ipsam.</p>
    <p>Eius odio placeat quidem porro fugit dolores, praesentium animi sit. Sunt, laboriosam illo iure pariatur, libero natus quo laudantium exercitationem optio totam, ratione maiores temporibus voluptate vitae in reiciendis perferendis!</p>
    <p>Eius ex, temporibus, provident natus accusamus, rerum illum perferendis quis eum minima culpa. Omnis accusamus, aut iusto perferendis rerum est, harum quo nisi, consequuntur in corrupti magni saepe culpa quisquam!</p>
    <p>Dolorum facilis rem earum nesciunt error doloremque excepturi sit incidunt nemo perferendis assumenda, animi et reprehenderit ea vero maiores aliquam totam distinctio neque alias debitis. Neque similique saepe obcaecati temporibus.</p>
  </h1>
</main>
!

CSS 

              
                .main {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  gap: 64px;
  margin: 32px auto;
  padding-inline: 16px;
  width: clamp(320px, 100%, 50rem);
}

.section {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

h1 {
  font-size: 3rem;
}

* {
  margin: 0;
}

h2 {
  font-size: 2rem;
}
!

JS
!
999px

Console