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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

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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 

              
                <div>*</div>
!

CSS 

              
                div {
  width: 100vmin;
  height: 100vmin;
  
  --primary: hsl(346, 70%, 50%);
  --secondary: hsl(196, 70%, 95%);
  --light: hsla(196, 90%, 98%, .4);
  
  --angle-start: 20vmin;
  --angle-degrees: 35deg;
  --background-angle-gradient: linear-gradient(var(--angle-degrees), transparent calc(var(--angle-start) - var(--angle-offset, 2vmin)), var(--secondary) var(--angle-start), transparent calc(var(--angle-start) + var(--angle-offset, 2vmin)));
  
  /* You can have multiple gradients in one variable... that can then be in a fuller multiple value `background` */
  --background-box:
      linear-gradient(90deg, var(--primary) 40%, var(--primary) 60%),
      linear-gradient(to bottom, var(--primary) 4%, transparent 4%, transparent 96%, var(--primary) 96%),
      linear-gradient(to right, var(--primary) 4%, var(--secondary) 4%, var(--secondary) 96%, var(--primary) 96%);
  --background-box-width: 40vmin;
  --background-box-height: 20%;
  
  --background-circle: radial-gradient(circle at 66.7% 66.7%, var(--secondary) 0, var(--secondary) 5vmin, transparent var(--radial-offset, 10vmin));
  
  --background-back:  linear-gradient(to bottom, var(--light), var(--light));
  
  background-image: 
    var(--background-angle-gradient),
    var(--background-box), 
    var(--background-circle);
  background-repeat: no-repeat;
  background-position: 
    center center,
    calc(var(--box-x, 20vmin) + 10vmin) 23%,
    var(--box-x, 20vmin) 20%,
    var(--box-x, 20vmin) 20%,
    center center;
  background-size: 
    auto,
    calc(var(--background-box-width) / 2) calc(var(--background-box-height) / 2),
    var(--background-box-width) var(--background-box-height),
    var(--background-box-width) var(--background-box-height),
    auto;
  
  color: rgba(0,0,0,0);
  text-shadow: -46vmin -40vmin .25vmin var(--sparkle-color-1),
    -48vmin -13vmin .5vmin var(--sparkle-color-2),
    -44vmin 13vmin .85vmin var(--sparkle-color-3),
    -46vmin 40vmin .15vmin var(--sparkle-color-4),
    
    46vmin -40vmin .65vmin var(--sparkle-color-1),
    44vmin -13vmin .5vmin var(--sparkle-color-2),
    48vmin 13vmin .75vmin var(--sparkle-color-3),
    46vmin 40vmin .35vmin var(--sparkle-color-4),
    
    -40vmin -46vmin .95vmin var(--sparkle-color-1),
    -14vmin -48vmin .25vmin var(--sparkle-color-2),
    14vmin -44vmin .55vmin var(--sparkle-color-3),
    40vmin -46vmin .5vmin var(--sparkle-color-4),
    
    -40vmin 46vmin .65vmin var(--sparkle-color-1),
    -15vmin 44vmin .15vmin var(--sparkle-color-2),
    15vmin 48vmin .95vmin var(--sparkle-color-3),
    41vmin 46vmin .65vmin var(--sparkle-color-4);
  
  transition: text-shadow 700ms ease-in-out;
  font-size: 5vmin;
  
  display: flex;
  justify-content: center;
  align-items: center;
}




body {
  overflow: hidden;
  background: hsl(196, 70%, 12%);
  display: flex;
  justify-content: center;
  align-items: flex-end;
  min-height: 100vh;
}
!

JS 

              
                var div = document.querySelector('div');
var style = div.style;

//The following variable names match the appropriate CSS Variables
var anglePosition = parseFloat(getComputedStyle(div).getPropertyValue('--angle-start')); //You can get the default value from the default CSS...
var angleOffset = 2; //... or use your own starting value
var angleDegrees = parseFloat(getComputedStyle(div).getPropertyValue('--angle-degrees'));
var boxX = 20;
var radialOffset = 10;

//Additional variables used in the requestAnimationFrame
var goUp = false;
var STEP_AMOUNT = .1;
var MAX_VMIN_VALUE = 32;
var MIN_VMIN_VALUE = 14;

requestAnimationFrame(move);

//This examples keeps things simple with linear easing.  You could certainly make these ease in, out, etc, and you could also make them respond to user interaction
function move() {
  //Setup new angled gradient value, adjusting both the background position and the gradient's color stop offset
  anglePosition = anglePosition + (goUp ? STEP_AMOUNT : -STEP_AMOUNT);
  angleOffset = angleOffset + ((goUp ? STEP_AMOUNT : -STEP_AMOUNT) / 4);
  angleDegrees = angleDegrees + ((goUp ? STEP_AMOUNT : -STEP_AMOUNT) * 1.25);
  style.setProperty('--angle-start', anglePosition + 'vmin');
  style.setProperty('--angle-offset', angleOffset + 'vmin');
  style.setProperty('--angle-degrees', angleDegrees + 'deg');
  
  //New x position value for the 2 gradients that make the box. This could alternately be done inside the gradients instead of the `background-position` var
  boxX = boxX + ((goUp ? -STEP_AMOUNT : STEP_AMOUNT) / .8);
  style.setProperty('--box-x', boxX + 'vmin');
  
  //New color stop distance for the radial gradient
  radialOffset = radialOffset + ((goUp ? -STEP_AMOUNT : STEP_AMOUNT));
  style.setProperty('--radial-offset', radialOffset + 'vmin');
  
  //change directions periodically
  if (anglePosition > MAX_VMIN_VALUE || anglePosition < MIN_VMIN_VALUE) {
    goUp = !goUp;
  }
  requestAnimationFrame(move);
}


//Make the sparkles sparkle. Combines with a CSS Transition for the fade in and out effect
//Could be simpler if Firefox allowed calc inside rgba... but the following will have broader support
setInterval(function() {
  style.setProperty('--sparkle-color-1', getColor());
  style.setProperty('--sparkle-color-2', getColor());
  style.setProperty('--sparkle-color-3', getColor());
  style.setProperty('--sparkle-color-4', getColor());
}, 700);
function getColor() {
  return 'rgba(240, 249, 208, ' + (Math.random() * .8) + ')';
}
!
999px

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