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About the <head>
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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.
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.
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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If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.
<summary>Spoiler about Star Wars</summary>
<div>Darth Vader is Anakin Skywalker, the father of Luke Skywalker.</div>
<p>...dolor sit met...</p>
<summary>Warning: graphic content</summary>
<div><img src="https://i.pinimg.com/474x/69/77/b7/6977b70a129ec184527433bbdf9fe457.jpg" alt="cat" /></div>
<p>...consectetur adipiscing elit.</p>