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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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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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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 

              
                <div class="description">
  fixedpos tooltip + position-visibility: anchors-visible.
</div>
<div class="scroller">
  <div class="item">Item 0</div>
  <div class="item">Item 1</div>
  <div class="item" id="anchor">Item 2</div>
  <div class="item">Item 3</div>
  <div class="item">Item 4</div>
  <div class="item">Item 5</div>
  <div class="item">Item 6</div>
  <div class="item">Item 7</div>
  <div class="item">Item 8</div>
  <div class="item">Item 9</div>
  <div class="item">Item 10</div>
  <div id="anchor-top-anchor"></div>
  <div id="tooltip">The best item!</div>
</div>
!

CSS 

              
                .description {
  font-family: 'Arial', sans-serif;
  font-size: small;
}

.scroller {
  position: relative;
  width: 300px;
  height: 150px;
  overflow-y: scroll;
  border: 2px solid #e0e0e0;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.15);
  border-radius: 4px;
  background-color: #f8f8f8;
  font-family: 'Arial', sans-serif;
  font-size: large;
}

.item {
  padding: 10px;
  margin-top: 1px;
  background-color: #fff;
  color: #333;
  transition: background-color 0.2s ease;
}

.item:hover {
  background-color: #ffebc5;
}

#anchor {
  anchor-name: --anchor;
  background-color: orange;
}

/* Fake anchor at the top of the real anchor */
/* Used for showing the tooltip only when the top of the anchor is visible. */
#anchor-top-anchor {
  anchor-name: --anchor-top-anchor;
  position-anchor: --anchor;
  bottom: anchor(--anchor top);
  position: absolute;
  left: 0;
}

#tooltip {
  pointer-events: none;
  position: fixed;
  position-anchor: --anchor-top-anchor;
  position-visibility: anchors-visible;
  position-try-options: flip-block;
  bottom: anchor(--anchor-top-anchor top);

  padding: 10px;
  background-color: #333;
  color: #f0f0f0;
  text-align: center;
  border-radius: 4px;
  margin: 0 5px 5px 5px;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
  font-size: 14px;
  filter: drop-shadow(4px 4px 4px rgba(50,50,50,0.3));
}

#tooltip::after {
  content: " ";
  position: absolute;
  top: 100%;
  left: 50%;
  margin-left: -5px;
  border-width: 5px;
  border-style: solid;
  border-color: black transparent transparent transparent;
}

@supports not (position-visibility: anchors-visible) {
  #tooltip {
    display: none;
  }
}

body {
  padding: 5rem;
}
!

JS
!
999px

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