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HTML

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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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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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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 

              
                <h2>Flex</h2>
<section class="flex">
  <div class="item">1</div>
  <div class="item">2</div>
  <div class="item">3</div>
</section>

<h2>Flex grow</h2>
<section class="flex">
  <div class="item flex-grow">1</div>
  <div class="item flex-grow">2</div>
  <div class="item flex-grow">3</div>
</section>

<h2>Flex grow 2</h2>
<section class="flex">
  <div class="item">1</div>
  <div class="item flex-grow">2</div>
  <div class="item">3</div>
</section>

<h2>Flex grow 3</h2>
<section class="flex">
  <div class="item flex-grow-2">1</div>
  <div class="item flex-grow">2</div>
  <div class="item flex-grow-2">3</div>
</section>

<h2>Flex wrap</h2>
<section class="flex flex-wrap">
  <div class="item flex-grow">1</div>
  <div class="item flex-grow">2</div>
  <div class="item flex-grow">3</div>
  <div class="item flex-grow" style="width: 100%;">3</div>
</section>

<h2>Flex push</h2>
<section class="flex">
  <div class="item item-50 item-dashed item-left flex-grow">Header</div>
  <div class="item">Action</div>
</section>

<h2>Align items</h2>
<section class="flex align-items">
  <div class="item" style="height: 200px;">Big</div>
  <div class="item">Small</div>
</section>

<h2>Justify content</h2>
<section class="flex justify-content">
  <div class="item">1</div>
  <div class="item">2</div>
</section>

<h2>Direction</h2>
<section class="flex flex-direction-column" style="height: 200px">
  <div class="item">1</div>
  <div class="item flex-grow">2</div>
</section>

<h2>Flex basis</h2>
<section class="flex flex-wrap">
  <div class="item flex-grow flex-shrink flex-basis">1</div>
  <div class="item flex-grow flex-shrink flex-basis">2</div>
  <div class="item flex-grow flex-shrink flex-basis">3</div>
</section>

<h2>Center div</h2>
<section class="item item-50 item-dashed flex align-items justify-content-center" style="height: 200px; width: 200px;">
  <div class="item item-dark">X</div>
</section>
!

CSS 

              
                .flex {
  display: flex;
  gap: 0.5rem;
}

.flex-direction-column {
  flex-direction: column;
}

.flex-wrap {
  flex-wrap: wrap;
}

.flex-shrink {
  flex-shrink: 1;
}

.flex-grow {
  flex-grow: 1;
}

.flex-grow-2 {
  flex-grow: 2;
}

.flex-grow-100 {
  flex-grow: 100;
}

.align-items {
  align-items: center;
}

.justify-content {
  justify-content: space-between;
}

.justify-content-center {
  justify-content: center;
}

.flex-basis {
  flex-basis: 500px;
}
!

JS
!
999px

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