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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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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 

              
                <article class="cubed" role="img" aria-label="Cartoon of a broken cube"></article>
!

CSS 

              
                body {
  --b: #3698;
  background: var(--b);
}

.cubed {
  --s: 200px;
  width: var(--s);
  height: var(--s);
  position: absolute;
  top: 35%;
  left: 50%;
  transform: translate(-50%, -50%) perspective(1000px) rotate3d(1,0,0, 60deg) rotate3d(0,0,1, 45deg);
  transform-style: preserve-3d;
  background:
    linear-gradient(#eee 75%, #0000 0),
    linear-gradient(90deg, #eee 75%, #0000 0),
    conic-gradient(at 75% 75%, #fff 135deg, #ddd 0);
  box-shadow: 
    290.75px 189px 0 -76.75px #eee,
    /* correction :S */
    76px 75px 0 -75.25px #fff,
    75px 76px 0 -75.25px #ddd
    ;
  background-repeat: no-repeat;
}

.cubed::before {
  content: "";
  position: absolute;
  top: 0;
  left: 100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(#f006, #00f6);
  transform-origin: 0 50%;
  transform: rotateX(-90deg) rotateY(90deg) translate(-50%, 50%);
  background:
    linear-gradient(#ddd0 25%, #ddd 0),
    linear-gradient(90deg, #ddd0 25%, #ddd 0),
    conic-gradient(at 25% 25%, #eee 315deg, #fff 0);
  background-repeat: no-repeat;
  box-shadow: 114px 299px 0 -60px #ddd;
}

.cubed::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 0;
  width: 100%;
  height: 100%;
  transform-origin: 50% 0;
  transform: rotateX(-90deg);
  background:
    linear-gradient(#fff0 25%, #fff 0),
    linear-gradient(90deg, #fff 75%, #fff0 0),
    conic-gradient(at 75% 25%, #ddd 45deg, #eee 0);
  background-repeat: no-repeat;
  box-shadow: 200px 70px 0 -70px #fff;
}
!

JS
!
999px

Console