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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-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

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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 

              
                <div class="wrapper">
  <div>Cell</div>
  <div>Cell</div>
  <div class="area e">Area E</div>
  <div>Cell</div>
  <div>Cell</div>
  <div class="area f">Area F</div>
  <div>Cell</div>
  <div class="area a">Area A</div>
  <div>Cell</div>
  <div>Cell</div>
  <div>Cell</div>
  <div class="area d">Area D</div>
  <div>Cell</div>
  <div class="area b">Area B</div>
  <div>Cell</div>
  <div class="area c">Area C</div>
</div>
!

CSS 

              
                .wrapper {
  display: grid; // Hey, this is a grid layout
  // grid-template-columns: 1fr 1fr 1fr 1fr 1fr; 
  /* instead of '1fr 1fr 1fr 1fr 1fr' for 5 columns, you can use the repeat() syntax if they're all going to be one size
  */
  grid-template-columns: repeat(5, 1fr); // for a 12-column grid, you can easily have it with repeat(12, 1fr)
  grid-template-rows: 1fr 1fr 1fr 1fr 1fr; // using fr avoids margin and padding issues
  grid-gap: 0.5em;
  grid-template-areas:
    "A A A B E"
    "C D D B F";
  // grid-template-areas:
  //   "b"; // will show only area B on the grid
  div {
    background: gainsboro;
    padding: 1em;
  }
  
  .a {
    grid-area: A; // Place it at the 'A' position in the grid template
    background: pink;
    content: "Area A";
  }
  .b {
    grid-area: B;
    background: lightgreen;
  }
  .c {
    grid-area: C;
    background: paleturquoise;
  }
  .d {
    grid-area: D;
    background: plum;
  }
  .e {
    grid-area: E;
    background: lavender;
  }
  .f {
    grid-area: F;
    background: papayawhip;
  }
}
!

JS
!
999px

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