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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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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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HTML 

              
                
 <h1>Highlighting images lacking an alt tag</h1>
  <p>This can be tested using just a bit of css. I wouldn't make this a permanent part of my stylesheet, but it could be added to the bottom of the style sheet before a project is launched just to see if all of my images have alt tags.</p>
  <p>To do this, the style sheet will create a black border around all images with an alt tag present. Next, it will create a red border around any images that don't have an alt tag. The css code to do this is:</p>
  <pre>img[alt] {border: solid 5px black;}
img {border:solid 5px red;}</pre>
   <h2>This is an image with an alt tag:</h2>
  <p>It should have a black border that is 5px thick.</p>
  <img src="http://kelliwise.com/wp-content/uploads/2017/11/Screen-Shot-2017-11-14-at-12.01.15-PM-300x170.png" alt="image with alt tag" />
  <hr />
  <h2>This is an image without an alt tag:</h2>
  <p>It should have a red border that is 5px thick.</p>
    <img src="http://kelliwise.com/wp-content/uploads/2017/11/Screen-Shot-2017-11-14-at-12.01.15-PM-300x170.png" />
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CSS 

              
                h2 {clear:both; color:blue;}

img {border:solid 5px red;}
img[alt] {border: solid 5px black;}
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JS
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999px

Console