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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

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. So you don't have access to higher-up elements like the <html> tag. If you want to add classes there that can affect the whole document, this is the place to do it.

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.

!
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).

Add External Stylesheets/Pens

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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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HTML 

              
                <div class="box box--fixed">
  <pre>fixed</pre>
</div>

<div class="box box--absolute">
  <pre>absolute</pre>
</div>

<p>
  Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam ac tellus interdum elit ultrices accumsan condimentum sed nibh. Nulla mauris turpis, dapibus ac euismod vitae, feugiat sit amet justo. Sed leo orci, elementum a faucibus vitae, iaculis eu
  nisl. In eu semper urna, sed porta lorem. Quisque consequat vehicula velit, sed imperdiet justo eleifend eget. Mauris auctor quis justo eu tempor. Praesent ac dolor arcu. Aliquam erat volutpat. Ut eu magna et magna faucibus euismod quis sit amet dui.
</p>
<p>
  Praesent sit amet felis justo. Donec in augue id lectus dapibus ullamcorper. Integer dapibus nunc eu eros porta, non hendrerit quam euismod. Proin pulvinar, tortor vitae fringilla mollis, ipsum risus rutrum erat, sed vestibulum nisl risus a ex. Aliquam
  mollis arcu a eros finibus blandit. Vestibulum viverra justo vitae quam sodales, ut pretium risus hendrerit. Suspendisse potenti. Morbi facilisis congue eros. Nam non porta arcu, a pharetra metus.
</p>
<p>
  Praesent non diam vel nibh placerat tristique sit amet elementum arcu. Aliquam erat volutpat. Donec fermentum, urna eget vehicula pulvinar, lacus enim aliquam leo, non tristique magna sapien et elit. Vestibulum purus justo, elementum vitae ex et, iaculis
  venenatis nisl. In scelerisque erat sit amet diam iaculis, nec bibendum lorem consequat. Sed dignissim et nibh sed vehicula. Vestibulum ex libero, feugiat sed turpis luctus, ultrices ullamcorper ante. Vivamus viverra dolor mauris, pretium porttitor
  lacus venenatis eu. Sed viverra neque risus, vitae rhoncus est sagittis eget.
</p>
<p>
  Aenean lectus erat, tempus at augue ac, mattis molestie est. Vestibulum vulputate eleifend odio et tristique. Mauris sed tellus volutpat, hendrerit leo vitae, mattis turpis. Fusce a risus vehicula mauris consectetur fermentum nec ac metus. Curabitur fringilla
  tempor sapien at bibendum. Fusce sed leo dictum, luctus leo ac, bibendum dolor. Phasellus erat ante, bibendum eu tempor non, commodo a lorem. Phasellus diam velit, ornare quis nisl et, finibus finibus ligula. Phasellus quis mi semper, bibendum ipsum
  nec, tristique metus. Aenean sit amet sem felis. Donec bibendum porttitor ipsum id imperdiet.
</p>
<p>
  Nunc id venenatis turpis. Etiam quis porttitor nisi, eu fringilla lorem. Praesent sed urna malesuada, pulvinar velit at, porttitor arcu. Aliquam in mi urna. Vivamus vel tellus eros. Phasellus lacus ipsum, luctus id sapien in, lobortis molestie diam. Quisque
  eu urna dictum, euismod arcu id, feugiat risus. Ut at ultrices lectus. Aenean posuere tempor ipsum, et vestibulum velit. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Cras in est non quam aliquet placerat. Aliquam
  ornare vitae risus sed tincidunt. Maecenas ut venenatis ipsum, a posuere urna. Fusce sagittis ligula a neque hendrerit eleifend. Sed non mauris quis tortor porttitor malesuada et vitae arcu. Nam sit amet tincidunt nibh, non feugiat magna.
</p>
<p>
  Fusce scelerisque, est ut accumsan fringilla, diam sapien feugiat nibh, a molestie augue justo sed leo. Maecenas sit amet odio tempor, faucibus mauris gravida, semper odio. Nam velit ipsum, efficitur ut velit nec, rutrum facilisis nibh. Nunc eu quam non
  orci tincidunt semper. Quisque quis tincidunt nisl, vitae maximus magna. Suspendisse leo orci, dapibus quis mi ac, maximus fringilla mi. Mauris a purus est. Morbi ultricies elementum turpis at congue.
</p>
<p>
  Morbi tincidunt, nibh at fermentum sollicitudin, libero elit feugiat est, id porttitor augue nisi sed tortor. Pellentesque laoreet purus libero, in sodales lacus convallis bibendum. Sed quis bibendum eros. Proin et pulvinar arcu. Nam faucibus, lacus vitae
  rutrum tristique, nisi tellus congue magna, quis tristique neque lorem ut dui. Phasellus fermentum tellus at risus malesuada ullamcorper. Quisque nec metus non tortor rutrum consectetur. Fusce ac tellus id ex sagittis commodo malesuada in turpis. In
  eleifend tristique maximus.
</p>
<p>
  Nullam sed orci sed magna laoreet ornare sed a augue. Donec urna leo, bibendum non ornare rutrum, porta in justo. Maecenas commodo congue dolor, eu cursus ex scelerisque eu. In eget tincidunt augue, at varius arcu. In tincidunt et risus non scelerisque.
  Vivamus sem leo, bibendum nec ultrices in, venenatis semper mi. Duis sodales lobortis urna, ac consequat arcu eleifend ullamcorper. Praesent metus ligula, porttitor eu congue sed, dignissim quis nisi. Vestibulum sed cursus nisi. Morbi varius, nulla
  in placerat feugiat, sapien neque consectetur lacus, sed maximus nunc odio et lectus. Mauris porttitor euismod augue vel egestas.
</p>
<p>
  Duis a euismod diam, vitae iaculis erat. Phasellus auctor dapibus ex, sed maximus turpis malesuada in. Aliquam rutrum erat nisi, ac cursus enim viverra in. Quisque porta aliquet massa in sollicitudin. Etiam gravida lectus libero, id volutpat magna sodales
  in. Aliquam ac nibh imperdiet, imperdiet felis sit amet, eleifend neque. Nam ut metus at nibh mattis ullamcorper et at nulla. Praesent dapibus vestibulum sagittis. Aenean lobortis, massa in convallis aliquet, nulla lectus consectetur ligula, et luctus
  lorem quam interdum neque. Donec nec condimentum lorem. Suspendisse ut scelerisque risus. Nulla eget turpis ut eros vulputate condimentum non nec sapien. Aliquam ut maximus turpis. Aliquam vitae dapibus nisl, quis dictum nibh. Vivamus et dolor massa.
</p>
<p>
  Donec suscipit tellus turpis, id commodo orci sagittis id. Proin ac sapien sit amet risus euismod cursus. Curabitur non risus efficitur, laoreet enim sit amet, congue libero. Curabitur nec metus non metus vehicula semper ut sed felis. Duis non convallis
  elit. Mauris massa dolor, vestibulum sit amet dolor ut, gravida convallis nisi. Nunc volutpat lectus libero, sed lacinia lorem lobortis sit amet. Integer sagittis vitae augue non ultrices. Curabitur a hendrerit nulla, eget efficitur purus. Nunc sed
  tristique elit, eleifend auctor est. Sed elementum, lectus sed elementum imperdiet, purus neque condimentum nisl, ac facilisis elit purus eu lorem. Sed non mattis dolor. Interdum et malesuada fames ac ante ipsum primis in faucibus.
</p>
!

CSS 

              
                p {
  font-family: sans-serif;
  color: LightGray;
}

.box {
  width: 10rem;
  height: 10rem;
  display: flex;
  justify-content: center;
  align-items: center;
  top: 50px;
}

.box--absolute {
  position: absolute;
  background-color: Pink;
  left: 200px;
}

.box--fixed {
  position: fixed;
  background-color: SandyBrown;
}

body {
  min-height: 5000px;
}
!

JS
!
999px

Console