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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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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

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JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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HTML 

              
                
<section class="what?">
	<h2>What is this?</h2>
	<p>Each of these containers has fluid typography with different easing techniques applied. Although they all have the same minimum and maximum sizes the transitions will be subtly different. <strong>Resize this window to see.</strong></p>
	
	<P>If you just want to <a target="_blank" href="https://www.sassmeister.com/gist/beac01f68da4f9ef3007c0d17f72d8c6">grab the mixin you can find it here</a>.</p>
	
	<P>If you want to read more about why I made this read <a target="_blank"  href="https://madebymike.com.au/writing/interpolation-without-animation/">Interpolation without animation</a>
and <a target="_blank" href="https://madebymike.com.au/writing/non-linear-interpolation-in-css/">Non-linear interpolation in CSS</a>.
		</p>
</section>

<section class="classic-linear">
	<h2>Classic Linear</h2>
	<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sint nisi, adipisci libero vitae deserunt iusto facilis expedita placeat quisquam fugit eligendi ipsum illum distinctio qui unde incidunt iure exercitationem voluptatem.</p>
	<pre>
.classic-linear {
  @include interpolate('font-size', 600px, 12px, 900px, 24px);
}</pre>
<span class="logger"></span> 
</section>	

<section class="easy-peasy">
	<h2>Easy Peasy</h2>
	<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sint nisi, adipisci libero vitae deserunt iusto facilis expedita placeat quisquam fugit eligendi ipsum illum distinctio qui unde incidunt iure exercitationem voluptatem.</p>
		<pre>
.easy-peasy {
  @include interpolate('font-size', 600px, 12px, 900px, 24px, 'ease-in');
}</pre>
<span class="logger"></span>
</section>	


<section class="cubic-bezier">
	<h2>Cubic Bezier</h2>
	<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sint nisi, adipisci libero vitae deserunt iusto facilis expedita placeat quisquam fugit eligendi ipsum illum distinctio qui unde incidunt iure exercitationem voluptatem.</p>
		<pre>
.cubic-bezier {
  @include interpolate('font-size', 600px, 12px, 900px, 24px, 'cubic-bezier(0.42, 0, 1, 1)');
}</pre>
<span class="logger"></span>
</section>	

<section class="bloat-my-css">
	<h2>Bloat My CSS</h2>
	<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sint nisi, adipisci libero vitae deserunt iusto facilis expedita placeat quisquam fugit eligendi ipsum illum distinctio qui unde incidunt iure exercitationem voluptatem.</p>
		<pre>
.bloat-my-css {
  @include interpolate('font-size', 600px, 12px, 900px, 24px, 'ease-in-ease-out', 6);
}</pre>
<span class="logger"></span>
</section>
!

CSS 

              
                // interpolate()

// This mixin generates CSS for interpolation of length properties.
// It has 5 required parameters, including the target property, initial
// screen size, initial value, final screen size and final value.

// It has two optional parameters which include an easing property, 
// which is a string representation of a CSS animation-timing-function, 
// and finally a number of bending-points that determines how many 
// interpolations steps are applied along the easing function.

///
/// @param {String} $property - The CSS property to interpolate
/// @param {Unit} $min-screen - A CSS length unit
/// @param {Unit} $min-value - A CSS length unit
/// @param {Unit} $max-screen - Value to be parsed
/// @param {Unit} $max-value - Value to be parsed
/// @param {String} $easing - Value to be parsed
/// @param {Number} $bending-points - Value to be parsed
///


/// EXAMPLES

.classic-linear {
	@include interpolate('font-size', 600px, 12px, 1000px, 24px); 
}
.easy-peasy {
	@include interpolate('font-size', 600px, 12px, 1000px, 24px, 'ease-in');
}
.cubic-bezier {
	@include interpolate('font-size', 600px, 12px, 1000px, 24px, 'cubic-bezier(0.75, 0.05, 0.85, 0.06)');
}
.bloat-my-css {
	@include interpolate('font-size', 600px, 12px, 1000px, 24px, 'ease-in-ease-out', 10); 
}


// Just for presentation, these styles do not relate to this technique

html {
	font-family: 'Muli', sans-serif;
	background: hsl(100, 50%, 95%);
}

@media screen and (min-width: 600px) {
	html{background: hsl(55, 50%, 95%);}
}

@media screen and (min-width: 1000px) {
	html{background: hsl(0, 50%, 95%);}
}

h2 {
	margin-top: 0;
}

section {
	padding: .75rem 1rem;
	margin: 1rem;
}

.classic-linear {
	background: hsl(90, 70%, 90%);
	border: solid 5px hsla(90, 70%, 50%, 0.25);
}
.easy-peasy {
	background: hsl(200, 70%, 90%);
	border: solid 5px hsla(200, 70%, 50%, 0.25);
}
.cubic-bezier {
	background: hsl(25, 70%, 90%);
	border: solid 5px hsla(25, 70%, 50%, 0.25);
}
.bloat-my-css {
	background: hsl(240, 70%, 90%);
	border: solid 5px hsla(240, 70%, 50%, 0.25);
}

pre {
	background: #eaeaea;
	padding: .5em;
	border: solid 1px #999;
	font-size: 16px;
	display: none;
}

@media screen and (min-width: 1000px) {
	pre {
		display: block;
	}	
}

section {position: relative;}
.logger { 
	position: absolute;
	text-align: right;
	right: 0;
	bottom: 0;
	background: rgba(0,0,0,0.55);
	color: white;
	padding: 1px 3px;
	font-size: 10px;
}
.logger:empty {
	display: none;
}
!

JS 

              
                // Some very hacky JS to display the pixel values

(function() {
	var throttle = function(type, name, obj) {
		obj = obj || window;
		var running = false;
		var func = function() {
			if (running) { return; }
			running = true;
			requestAnimationFrame(function() {
				obj.dispatchEvent(new CustomEvent(name));
				running = false;
			});
		};
		obj.addEventListener(type, func);
	};

	/* init - you can init any event */
	throttle("resize", "optimizedResize");
})();

// handle event
var LogValues = function() {
	var root = document.documentElement;
	var sections = document.querySelectorAll('section')
	var viewportWidth = Math.max(document.documentElement.clientWidth, window.innerWidth || 0);	

	for (var i = 0; i < sections.length; i++) {
		var logger = sections[i].querySelector('.logger');
		if(logger){
			var style = window.getComputedStyle(sections[i], null);
			var fontSize = style.getPropertyValue("font-size");
			logger.innerHTML = 'font-size: ' + (Math.round(parseFloat(fontSize,10) * 100) / 100) + 'px';	
		}
	}
}

LogValues();
window.addEventListener("optimizedResize", LogValues);
!
999px

Console