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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

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 

              
                <!--Pattern HTML-->
  <div id="pattern" class="pattern">
    <img src="https://bradfrost.github.com/this-is-responsive/patterns/images/fpo_landscape.png" class="landscape" alt="FPO Image" />
	</div>
	<!--End Pattern HTML-->
	
	<div class="container">	
		<section class="pattern-description">
			<h1>Landscape Image</h1>
			<p>This is a very basic example of a fluid image that has a landscape orientation.</p>
			<h2>Considerations</h2>
			<ul>
				<li>Loading in massive images for mobile screens isn't a good idea from a performance standpoint. Load a small image by default.</li>
				<li>Content in the large landscape image may not be legible on small screens. <a href="http://blog.cloudfour.com/a-framework-for-discussing-responsive-images-solutions/">This post</a> demonstrates how a tighter crop might be required for smaller screens.</li>
				<li>Avoid text in images, especially for fluid images whose size are subject to change.</li>
			</ul>
		</section>
		<footer role="contentinfo">   
			<div>
				<nav id="menu">
					<a href="https://bradfrost.github.com/this-is-responsive/patterns.html">&larr;More Responsive Patterns</a>
				</nav>
			</div>
		</footer>
	</div>
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CSS 

              
                .landscape {
    display: block;
    max-width: 100%;
    height: auto;
  }
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JS
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999px

Console