Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

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JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

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Packages

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Behavior

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Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

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HTML

              
                <div class="input">
	<input class="input-control" id="input" placeholder="Placeholder" />
	<label class="input-label" for="input">This label is red when when the placeholder is shown, green otherwise, and blue in old browsers.</label>
</div>
              
            
!

CSS

              
                

.input
	&-label
		color: blue // For old browsers
	
	// This is the tricky part. Old browsers will discard the entire selector group as it contains an invalid selector. Newer browsers will match nothing for the first one but happily apply the rest.
	\:not(*):placeholder-shown,
	&-label
		color: green
	&-control:placeholder-shown ~ &-label
		color: red
              
            
!

JS

              
                
              
            
!
999px

Console