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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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About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient. For instance, CoffeeScript can help prevent easy-to-make mistakes and offer a cleaner syntax and Babel can bring ECMAScript 6 features to browsers that only support ECMAScript 5.

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You're using npm packages, so we've auto-selected Babel for you here, which we require to process imports and make it all work. If you need to use a different JavaScript preprocessor, remove the packages in the npm tab.

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About External Resources

You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.

If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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HTML

            
              <div class="buttons">
  <p class="intro">Click the <code>border-box</code> button to fix the layout with the power of Box Sizing!</p>
  <button id="content">content-box</button>
  <button id="border">border-box</button>
</div>

<div class="parent">
  <form class="twins" action="/action_page.php">
    First name:<br>
    <input type="text" name="firstname" value="Mickey"><br> Last name:<br>
    <input type="text" name="lastname" value="Mouse"><br> Comments:
    <br>
    <textarea name="message" rows="5" cols="30">
</textarea>
    <br><br>
    <input type="submit" value="Submit">
  </form>
  <form class="twins" action="/action_page.php">
    First name:<br>
    <input type="text" name="firstname" value="Mickey"><br> Last name:<br>
    <input type="text" name="lastname" value="Mouse"><br> Comments:
    <br>
    <textarea name="message" rows="5" cols="30">
</textarea>
    <br><br>
    <input type="submit" value="Submit">
  </form>
</div>
!

CSS

            
              .parent {
  width: 70%;
  border: 5px solid #E18728;
  float: left;
}

.child {
  width: 90%;
  padding: 20%;
  border: 4px solid black;
  margin: .5em auto;
}

.twins {
  width: 50%;
  padding: 1em;
  border: 4px solid black;
  float: left;
}

input, textarea {
    width: 100%;
}

body {
  font-family: sans-serif;
  font-size: 1.1em;
}

.buttons {
  margin-bottom: .5em;
}

p:not(.intro) {
  text-align: center;
}
!

JS

            
              $("#content").on("click", function() {
  $("*").css("box-sizing", $(this).text());
});

$("#border").on("click", function() {
  $("*").css("box-sizing", $(this).text());
});
!
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