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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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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

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.

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HTML 

              
                <p>
  Finally I found a way to make borders around my floated divs collapse like on table cells. The key was to use box-shadow instead of border. So this is actually a trick to <i>simulate</i> borders.
</p>

<p>
  I couldn't use <code>display:table-cell</code> because table cells don't get rearranged vertically the way I want in responsive scenarios.
</p>

<p class="info">
  You can try to resize the browser window to further explore how the "borders" behave.
</p>

<p>The first container:</p>

<div id="container1" class="container">
  <div>Hello, this is the first floated div</div>
  <div>And this is the second</div>
  <div>And finally the third one</div>
</div>

<p>The second container:</p>

<div id="container2" class="container">
  <div>Hello, this is the first floated div</div>
  <div>And this is the second</div>
  <div>And finally the third one</div>
</div>
!

CSS 

              
                body {
  font-family: sans-serif;
  background-color: #eee;
  padding: 20px;
}

.info {
  color: darkred;
  font-weight: bolder;
}

.container {
  background-color: white;
  float: left; /* Makes the container height the same as its children. */
  padding: 10px;
  margin-bottom: 40px;
}

.container div {
  padding: 20px;
  float: left;
  background-color: #def;
  
  
  /* And here comed the trick: */

  box-shadow: 
    2px 0 0 0 #888, 
    0 2px 0 0 #888, 
    2px 2px 0 0 #888,   /* Just to fix the corner */
    2px 0 0 0 #888 inset, 
    0 2px 0 0 #888 inset;

}

#container1 {
  width: 100%;
}

#container2 {
  width: 50%;
}

#container2 div {
  width: 70%;
}
!

JS
!
999px

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