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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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About the <head>

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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

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 

              
                <body>
<div class="row">
<div class="col-sm-3" id="spy">
  <ul class="nav nav-pills flex-column">
    <li class="nav-item"><a class="nav-link active" href="#scroll1">First Section</a></li>
    <li class="nav-item"><a class="nav-link" href="#scroll2">Second Section</a></li>
    <li class="nav-item"><a class="nav-link" href="#scroll3">Third Section</a></li>
    <li class="nav-item"><a class="nav-link" href="#scroll4">Fourth Section</a></li>
  </ul>
</div>
<div class="col-sm-9 scrollspy-example" data-spy="scroll" data-target="#spy">
  <div id="scroll1">
    <h2>First Section</h2>
    <p>
    During Compile time, the compiler converts the source code into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) are CPU-Independent set of instructions that can be effectively converted to the native code. Now with the help of JIT compiler, IL code can be executed on any computer architecture supported by the JIT compiler.
    </p>
  </div>
  <div id="scroll2">
    <h2>Second Section</h2>
    <p>
    During Compile time, the compiler converts the source code into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) are CPU-Independent set of instructions that can be effectively converted to the native code. Now with the help of JIT compiler, IL code can be executed on any computer architecture supported by the JIT compiler.
    </p>
  </div>
  <div id="scroll3">
    <h2>Third Section</h2>
    <p>
    During Compile time, the compiler converts the source code into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) are CPU-Independent set of instructions that can be effectively converted to the native code. Now with the help of JIT compiler, IL code can be executed on any computer architecture supported by the JIT compiler.
    </p>
  </div>
  <div id="scroll4">
    <h2>Fourth Section</h2>
    <p>
    During Compile time, the compiler converts the source code into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) are CPU-Independent set of instructions that can be effectively converted to the native code. Now with the help of JIT compiler, IL code can be executed on any computer architecture supported by the JIT compiler.
    </p>
    <p>
    During Compile time, the compiler converts the source code into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) are CPU-Independent set of instructions that can be effectively converted to the native code. Now with the help of JIT compiler, IL code can be executed on any computer architecture supported by the JIT compiler.
    </p>
    <p>
    During Compile time, the compiler converts the source code into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) are CPU-Independent set of instructions that can be effectively converted to the native code. Now with the help of JIT compiler, IL code can be executed on any computer architecture supported by the JIT compiler.
    </p>
    <p>
    During Compile time, the compiler converts the source code into Microsoft Intermediate Language (MSIL). Microsoft Intermediate Language (MSIL) are CPU-Independent set of instructions that can be effectively converted to the native code. Now with the help of JIT compiler, IL code can be executed on any computer architecture supported by the JIT compiler.
    </p>
  </div>
</div>
</div>
</body>
!

CSS 

              
                .scrollspy-example {
  position: relative;
  height: 250px;
  overflow: auto;
}
!

JS
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999px

Console