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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>

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. If you need things in the <head> of the document, put that code here.

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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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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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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 

              
                <body class="dark-mode with-custom-webkit-scrollbars with-custom-css-scrollbars" data-sidebar-shortcut-enabled="true" data-dm-shortcut-enabled="true">
	<div class="page-wrapper">
		<!-- Content wrapper -->
		<div class="content-wrapper">
			<div class="hoge">
				<button class="btn" type="button">Default</button>
				<button class="btn btn-primary" type="button">Primary</button>
				<button class="btn btn-danger" type="button">Danger</button>
			</div>
			<div class="hoge">
				<table class="table">
					<thead>
						<tr>
							<th>#</th>
							<th>First</th>
							<th>Last</th>
							<th class="text-right">Age</th>
						</tr>
					</thead>
					<tbody>
						<tr>
							<th>1</th>
							<td>John</td>
							<td>Doe</td>
							<td class="text-right">25</td>
						</tr>
						<tr>
							<th>2</th>
							<td>Jane</td>
							<td>Violet</td>
							<td class="text-right">27</td>
						</tr>
						<tr>
							<th>3</th>
							<td>Jack</td>
							<td>Gates</td>
							<td class="text-right">33</td>
						</tr>
					</tbody>
				</table>

			</div>
			<div class="hoge">
				<form action="..." method="..." class="w-400 mw-full">
					<!-- w-400 = width: 40rem (400px), mw-full = max-width: 100% -->
					<!-- Input -->
					<div class="form-group">
						<label for="full-name" class="required">Full name</label>
						<input type="text" class="form-control" id="full-name" placeholder="Full name" required="required">
					</div>

					<!-- Radio -->
					<div class="form-group">
						<label for="gender-male" class="required">Gender</label>
						<div class="custom-radio">
							<input type="radio" name="gender" id="gender-male" value="male" required="required">
							<label for="gender-male">Male</label>
						</div>
						<div class="custom-radio">
							<input type="radio" name="gender" id="gender-female" value="female" required="required">
							<label for="gender-female">Female</label>
						</div>
						<div class="custom-radio">
							<input type="radio" name="gender" id="gender-other" value="other" required="required">
							<label for="gender-other">Other</label>
						</div>
					</div>

					<!-- Select -->
					<div class="form-group">
						<label for="area-of-specialization" class="required">Area of specialization</label>
						<select class="form-control" id="area-of-specialization" required="required">
							<option value="" selected="selected" disabled="disabled">Select your area of specialization</option>
							<option value="front-end">Front-end</option>
							<option value="back-end">Back-end</option>
							<option value="full-stack">Full-stack</option>
						</select>
					</div>
			</div>
			<div class="hoge">
				<nav aria-label="Breadcrumb navigation example">
					<ul class="breadcrumb">
						<li class="breadcrumb-item"><a href="#">Home</a></li>
						<li class="breadcrumb-item"><a href="#">Docs</a></li>
						<li class="breadcrumb-item active" aria-current="page"><a href="#">Breadcrumb</a></li>
					</ul>
				</nav>
			</div>
			<div class="hoge">
				<div class="custom-switch">
					<input type="checkbox" id="switch-1" value="">
					<label for="switch-1">Switch 1</label>
				</div>
			</div>
			<div class="hoge"><button class="btn" data-toggle="tooltip" data-title="Default tooltip" type="button">
					Default
				</button>
				<button class="btn" data-toggle="tooltip" data-title="Top tooltip" data-placement="top" type="button">
					Top
				</button>
				<button class="btn" data-toggle="tooltip" data-title="Right tooltip" data-placement="right" type="button">
					Right
				</button>
				<button class="btn" data-toggle="tooltip" data-title="Bottom tooltip" data-placement="bottom" type="button">
					Bottom
				</button>
				<button class="btn" data-toggle="tooltip" data-title="Left tooltip" data-placement="left" type="button">
					Left
				</button></div>

		</div>
	</div>

</body>
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CSS 

              
                .hoge {
	margin: auto;
	margin-bottom: 30px;
	width: 80%;
}
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JS
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999px

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