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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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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-.

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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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 Skypack, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ES6 import usage.

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HTML 

              
                <form>
	<input class="ch" type="checkbox" name="temperature" value="is_hot">
</form>
!

CSS 

              
                *, *:before, *:after {
	box-sizing: border-box;
	margin: 0;
	padding: 0;
}
:root {
	font-size: calc(16px + (24 - 16) * (100vw - 320px)/(1600 - 320));
}
body {
	background: rgb(235,167,49);
	line-height: 1.5;
}
input {
	display: inline-block;
}
form {
	padding: 3em 1.5em 0 1.5em;
	text-align: center;	
}
.ch, .ch:before, .ch:after {
	transition: all 0.3s ease-in-out;
}
.ch {
	background-color: rgb(27,123,145);
	border-radius: 0.2em;
	box-shadow: 0 0.05em 0 0.05em rgba(0,0,0,0.3) inset;
	font-size: 4em;
	overflow: hidden;
	position: relative;
	width: 3em;
	height: 1.5em;
	-webkit-appearance: none;
	-moz-appearance: none;
	appearance: none;
	z-index: 0;
}
.ch:before, .ch:after {
	content: "";
	display: block;
	position: absolute;
}
.ch:before {
	background-color: currentColor;
	border-radius: 0.125em;
	box-shadow:
		0 0 0 0.05em inset,
		-0.12em -0.12em 0 rgb(109,148,184) inset,
		-0.4em -0.3em 0 0.05em inset,
		0.12em 0.12em 0 rgb(255,255,255) inset;
	color: rgb(149,188,224);
	opacity: 0.9;
	bottom: 0;
	left: 0.125em;
	width: 1.25em;
	height: 1.25em;
	z-index: 2;
}
.ch:after {
	background-image:
		/* white */
		radial-gradient(0.2em 0.5em at 38% 95%, rgb(255,255,255) 49%, rgba(255,255,255,0) 50%),
		radial-gradient(0.3em 0.8em at 52% 95%, rgb(255,255,255) 49%, rgba(255,255,255,0) 50%),
		radial-gradient(0.25em 0.4em at 67% 95%, rgb(255,255,255) 49%, rgba(255,255,255,0) 50%),
		/* yellow */
		radial-gradient(0.25em 0.7em at 36% 95%, rgb(255,224,0) 49%, rgba(255,224,0,0) 50%),
		radial-gradient(0.4em 1.2em at 52% 95%, rgb(255,224,0) 49%, rgba(255,224,0,0) 50%),
		radial-gradient(0.25em 0.6em at 70% 93%, rgb(255,224,0) 49%, rgba(255,224,0,0) 50%),
		/* orange */
		radial-gradient(0.3em 0.8em at 32% 81%, rgb(255,144,0) 49%, rgba(255,144,0,0) 50%),
		radial-gradient(0.5em 1.6em at 52% 95%, rgb(255,144,0) 49%, rgba(255,144,0,0) 50%),
		radial-gradient(0.3em 0.9em at 74% 86%, rgb(255,144,0) 49%, rgba(255,144,0,0) 50%),
		/* red-orange */
		radial-gradient(0.4em 1em at 25% 70%, rgb(255,76,0) 49%, rgba(255,76,0,0) 50%),
		radial-gradient(0.7em 2.75em at 52% 100%, rgb(255,76,0) 49%, rgba(255,76,0,0) 50%),
		radial-gradient(0.4em 1.2em at 79% 75%, rgb(255,76,0) 49%, rgba(255,76,0,0) 50%);

	background-position: 100% 1.5em;
	background-size: 1.5em 1.5em;
	background-repeat: no-repeat;
	border-radius: 0 0 0 0.1em / 0 0 0 0;
	box-shadow: 0 0 0 0 rgb(169,208,244) inset;
	bottom: 0;
	left: 0;
	width: 1.5em;
	height: 1.5em;
	z-index: 1;
}
/* Checked */
.ch:checked {
	background-color: rgb(92,8,8);
}
.ch:checked:before {
	border-radius: 50%;
	transform: translate(1.5em,1.5em) rotate(45deg) scale(0.5);
}
.ch:checked:after {
	background-position: 100% 0;
	box-shadow: 0 -0.15em 0 0 rgb(169,208,244) inset;
	width: 3em;
}

/* Other States */
.ch:focus {
	/* Usually an anti-A11Y practice but set to remove an annoyance just for this demo */
	outline: 0;
}
!

JS
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999px

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